@article{arifi_choi_ji_oh_2023, title={Independence of current components, polarization vectors, and reference frames in the light-front quark model analysis of meson decay constants}, volume={107}, ISSN={["2470-0029"]}, DOI={10.1103/PhysRevD.107.053003}, abstractNote={The issue of resulting in the same physical observables with different current components, in particular from the minus current, has been challenging in the light-front quark model (LFQM) even for the computation of the two-point functions such as meson decay constants. At the level of one-body current matrix element computation, we show the uniqueness of pseudoscalar and vector meson decay constants using all available components including the minus component of the current in the LFQM consistent with the Bakamjian-Thomas construction. Regardless of the current components, the polarization vectors, and the reference frames, the meson decay constants are uniquely determined in the noninteracting constituent quark and antiquark basis while the interactions of the constituents are added to the meson mass operator in the LFQM.}, number={5}, journal={PHYSICAL REVIEW D}, author={Arifi, Ahmad Jafar and Choi, Ho-Meoyng and Ji, Chueng-Ryong and Oh, Yongseok}, year={2023}, month={Mar} }
@article{ji_ji_2023, title={Interpolation Between Instant Form Dynamics and Light-Front Dynamics}, volume={1012}, ISBN={["978-981-19-7948-4"]}, ISSN={["1616-6361"]}, DOI={10.1007/978-981-19-7949-1_2}, abstractNote={Among the three distinctly different forms of relativistic Hamiltonian dynamics proposed by Dirac in 1949, the instant form and the front form can be interpolated by introducing an interpolation angle between the ordinary time t and the light-front time $$(t+z/c)/\sqrt{2}$$ . Using this method, we introduce the interpolating scattering amplitude that links the corresponding time-ordered amplitudes between the two forms of dynamics and provide the physical meaning of the kinematic transformations as they allow the invariance of each individual time-ordered amplitude for an arbitrary interpolation angle. In particular, it exhibits that the longitudinal boost is kinematical only in the front form dynamics, or the light-front dynamics (LFD), but not in any other interpolation angle dynamics. It also shows that the disappearance of the connected contributions to the current arising from the vacuum occurs when the interpolation angle is taken to yield the LFD. Since it does’nt require the infinite momentum frame (IMF) to show this disappearance and the proof is independent of reference frames, it resolves the confusion between the LFD and the IMF. The well-known utility of IMF usually discussed in the instant form dynamics is now also extended to any other interpolation angle dynamics using our interpolating scattering amplitudes.}, journal={RELATIVISTIC QUANTUM INVARIANCE}, author={Ji, Chueng-Ryong and Ji, CR}, year={2023}, pages={17–47} }
@article{ji_ji_2023, title={Interpolation of Quantum Chromodynamics in 1+1 Dimension}, volume={1012}, ISBN={["978-981-19-7948-4"]}, ISSN={["1616-6361"]}, DOI={10.1007/978-981-19-7949-1_4}, abstractNote={The ’t Hooft model, i.e. the two-dimensional quantum chromodynamics in the limit of infinite number of colors, is interpolated by an angle parameter $$\delta $$ between $$\delta =0$$ for the instant form dynamics (IFD) and $$\delta =\pi {/4}$$ for the light-front dynamics (LFD).}, journal={RELATIVISTIC QUANTUM INVARIANCE}, author={Ji, Chueng-Ryong and Ji, CR}, year={2023}, pages={111–171} }
@article{ji_ji_2023, title={Interpolation of Quantum Electrodynamics}, volume={1012}, ISBN={["978-981-19-7948-4"]}, ISSN={["1616-6361"]}, DOI={10.1007/978-981-19-7949-1_3}, abstractNote={The instant form and the front form of relativistic dynamics proposed by Dirac in 1949 can be linked by an interpolation angle parameter $$\delta $$ spanning between the instant form dynamics (IFD) at $$\delta =0$$ and the front form dynamics which is now known as the light-front dynamics (LFD) at $$\delta =\pi /4$$ .}, journal={RELATIVISTIC QUANTUM INVARIANCE}, author={Ji, Chueng-Ryong and Ji, CR}, year={2023}, pages={49–109} }
@misc{wang_he_ji_melnitchouk_2023, title={Nucleon form factors and parton distributions in nonlocal chiral effective theory}, volume={129}, ISSN={["1873-2224"]}, DOI={10.1016/j.ppnp.2022.104017}, abstractNote={We present a review of recent applications of nonlocal chiral effective theory to hadron structure studies. Starting from a nonlocal meson--baryon effective chiral Lagrangian, we show how the introduction of a correlation function representing the finite extent of hadrons regularizes the meson loop integrals and introduces momentum dependence in vertex form factors in a gauge invariant manner. We apply the framework to the calculation of nucleon electromagnetic form factors, unpolarized and polarized parton distributions, as well as transverse momentum dependent distributions and generalized parton distributions. Assuming that the nonlocal behavior is a general property of all interactions, we also discuss the application to the lepton anomalous magnetic moment in nonlocal QED.}, journal={PROGRESS IN PARTICLE AND NUCLEAR PHYSICS}, author={Wang, P. and He, Fangcheng and Ji, Chueng-Ryong and Melnitchouk, W.}, year={2023}, month={Mar} }
@article{copeland_ji_melnitchouk_2023, title={Octet and decuplet baryon sigma terms and mass decompositions}, volume={107}, ISSN={["2470-0029"]}, DOI={10.1103/PhysRevD.107.094041}, abstractNote={We present a comprehensive analysis of the SU(3) octet and decuplet baryon masses and $\ensuremath{\sigma}$ terms using high-precision lattice QCD data and chiral SU(3) effective theory with finite range regularization. The effects of various systematic uncertainties, including from the scale setting of the lattice data and the regularization prescriptions, are quantified. We find the pion-nucleon and strange nucleon $\ensuremath{\sigma}$ terms to be ${\ensuremath{\sigma}}_{\ensuremath{\pi}N}=44(3)(3)\text{ }\text{ }\mathrm{MeV}$ and ${\ensuremath{\sigma}}_{Ns}=50(6)(1)\text{ }\text{ }\mathrm{MeV}$, respectively. The results provide constraints on the energy-momentum tensor mass decompositions of the SU(3) octet and decuplet baryons, where we find that the trace anomaly and quark-gluon energies decrease for strange baryons due to their larger strange $\ensuremath{\sigma}$ terms.}, number={9}, journal={PHYSICAL REVIEW D}, author={Copeland, P. M. and Ji, Chueng-Ryong and Melnitchouk, W.}, year={2023}, month={May} }
@book{ji_2023, title={Relativistic Quantum Invariance}, ISBN={9789811979484 9789811979491}, ISSN={0075-8450 1616-6361}, url={http://dx.doi.org/10.1007/978-981-19-7949-1}, DOI={10.1007/978-981-19-7949-1}, abstractNote={This book describes the invariant nature of the relativistic quantum field theories utilizing the idea of interpolating the instant form dynamics}, journal={Lecture Notes in Physics}, publisher={Springer Nature Singapore}, author={Ji, Chueng-Ryong}, year={2023} }
@article{ji_ji_2023, title={Relativistic Quantum Invariance Introduction}, volume={1012}, ISBN={["978-981-19-7948-4"]}, ISSN={["1616-6361"]}, DOI={10.1007/978-981-19-7949-1_1}, abstractNote={In this chapter, we will discuss special relativity [1–3] established by Albert Einstein in 1905.}, journal={RELATIVISTIC QUANTUM INVARIANCE}, author={Ji, Chueng-Ryong and Ji, CR}, year={2023}, pages={1–16} }
@article{choi_choi_ji_oh_2022, title={Analysis of virtual meson production in a (1+1)-dimensional scalar field model}, volume={105}, ISSN={["2470-0029"]}, DOI={10.1103/PhysRevD.105.096014}, abstractNote={Light-front time-ordered amplitudes are investigated in the virtual scalar meson production process in (1+1) dimensions using the solvable scalar field theory extended from the conventional Wick-Cutkosky model. There is only one Compton form factor (CFF) in the (1+1) dimensional computation of the virtual meson production process, and we compute both the real and imaginary parts of the CFF for the entire kinematic regions of $Q^2>0$ and $t<0$. We then analyze the contribution of each and every light-front time-ordered amplitude to the CFF as a function of $Q^2$ and $t$. In particular, we discuss the significance of the "cat's ears" contributions for gauge invariance and the validity of the "handbag dominance" in the formulation of the generalized parton distribution (GPD) function used typically in the analysis of deeply virtual meson production processes. We explicitly derive the GPD from the "handbag" light-front time-ordered amplitudes in the $-t/Q^2<<1$ limit and verify that the integrations of the GPD over the light-front longitudinal momentum fraction for the DGLAP and ERBL regions correspond to the valence and nonvalence contributions of the electromagnetic form factor that we have recently reported [Phys. Rev. D $\textbf{103}$, 076002 (2021)]. We also discuss the correspondence of the GPD to the parton distribution function for the analysis of the deep inelastic lepton-hadron scattering process and the utility of the new light-front longitudinal spatial variable $\tilde{z}$.}, number={9}, journal={PHYSICAL REVIEW D}, author={Choi, Yongwoo and Choi, Ho-Meoyng and Ji, Chueng-Ryong and Oh, Yongseok}, year={2022}, month={May} }
@article{he_ji_melnitchouk_thomas_wang_2022, title={Generalized parton distributions of sea quarks in the proton from nonlocal chiral effective theory}, volume={106}, ISSN={["2470-0029"]}, DOI={10.1103/PhysRevD.106.054006}, abstractNote={We calculate the spin-averaged generalized parton distributions (GPDs) of sea quarks in the proton at zero skewness from nonlocal covariant chiral effective theory, including one-loop contributions from intermediate states with pseudoscalar mesons and octet and decuplet baryons. A relativistic regulator is generated from the nonlocal Lagrangian where a gauge link is introduced to guarantee local gauge invariance, with additional diagrams from the expansion of the gauge link ensuring conservation of electric charge and strangeness. Flavor asymmetries for sea quarks at zero and finite momentum transfer, as well as strange form factors, are obtained from the calculated GPDs, and results compared with phenomenological extractions and lattice QCD.}, number={5}, journal={PHYSICAL REVIEW D}, author={He, Fangcheng and Ji, Chueng-Ryong and Melnitchouk, W. and Thomas, A. W. and Wang, P.}, year={2022}, month={Sep} }
@article{he_ji_melnitchouk_salamu_thomas_wang_wang_2022, title={Helicity-dependent distribution of strange quarks in the proton from nonlocal chiral effective theory}, volume={105}, ISSN={["2470-0029"]}, DOI={10.1103/PhysRevD.105.094007}, abstractNote={The helicity-dependent strange quark distribution in the proton, $\Delta s$, is calculated in a nonlocal chiral SU(3) effective field theory. The hadronic proton to meson plus octet or decuplet baryon splitting functions are derived at the one-loop level, with loop integrals rendered finite by correlation functions introduced in the nonlocal Lagrangian. Within the convolution framework, the proton strange helicity distribution is obtained using spin-flavor symmetry to constrain the input valence quark distributions in the hadronic intermediate states. The polarized strange quark distribution is found to be quite small, with the lowest moment of $\Delta s$ negative, but consistent with recent global QCD analyses.}, number={9}, journal={PHYSICAL REVIEW D}, author={He, Fangcheng and Ji, Chueng-Ryong and Melnitchouk, W. and Salamu, Y. and Thomas, A. W. and Wang, P. and Wang, X. G.}, year={2022}, month={May} }
@article{arifi_choi_ji_oh_2022, title={Mixing effects on 1S and 2S state heavy mesons in the light-front quark model}, volume={106}, ISSN={["2470-0029"]}, DOI={10.1103/PhysRevD.106.014009}, abstractNote={The mass spectra and wave functions of both $1S$ and $2S$ state heavy pseudoscalar ($P$) and vector ($V$) mesons are analyzed within the light-front quark model. Important empirical constraints employed in our analysis of the mass spectra and wave functions are the experimental mass-gap relation, $\mathrm{\ensuremath{\Delta}}{M}_{P}>\mathrm{\ensuremath{\Delta}}{M}_{V}$, where $\mathrm{\ensuremath{\Delta}}{M}_{P(V)}={M}_{P(V)}^{2S}\ensuremath{-}{M}_{P(V)}^{1S}$ and the hierarchy of the decay constants, ${f}_{1S}>{f}_{2S}$, between $1S$ and $2S$ meson states. We maintain the orthogonality of the trial wave functions of the $1S$ and $2S$ states in our variational calculation of the Hamiltonian with the Coulomb plus confining potentials and treat the hyperfine interaction perturbatively for the heavy-heavy and heavy-light $P$ and $V$ mesons due to the nature of the heavy quark symmetry. Realizing that the empirical constraints cannot be satisfied without mixing of the $1S$ and $2S$ states, we find the lower bound of the mixing angle $\ensuremath{\theta}$ between $1S$ and $2S$ states as ${\ensuremath{\theta}}_{c}={\mathrm{cot}}^{\ensuremath{-}1}(2\sqrt{6})/2\ensuremath{\simeq}6\ifmmode^\circ\else\textdegree\fi{}$ and obtain the optimum value of the mixing angle around 12\ifmmode^\circ\else\textdegree\fi{} to cover both the charm and bottom flavors of the heavy quark. The mixing effects are found to be more significant to the $2S$ state mesons than to the $1S$ state mesons. The properties of $1S$ and $2S$ state mesons including the mass spectra, decay constants, twist-2 distribution amplitudes, and electromagnetic form factors are computed. Our results are found to be in a good agreement with the available data and lattice simulations. In particular, the $2S$ state pseudoscalar ${D}_{s}$ meson is predicted to have a mass of 2600 MeV, which is very close to the mass of the newly discovered ${D}_{s0}(2590{)}^{+}$ meson by the LHCb Collaboration. This supports the interpretation of the observed state as a radial excitation of the ${D}_{s}^{+}$ meson.}, number={1}, journal={PHYSICAL REVIEW D}, author={Arifi, Ahmad Jafar and Choi, Ho-Meoyng and Ji, Chueng-Ryong and Oh, Yongseok}, year={2022}, month={Jul} }
@article{ji_mishchenko_2021, title={General Quantum Field Theory of Flavor Mixing and Oscillations}, volume={7}, ISSN={["2218-1997"]}, DOI={10.3390/universe7030051}, abstractNote={We review the canonical transformation in quantum physics known as the Bogoliubov transformation and present its application to the general theory of quantum field mixing and oscillations with an arbitrary number of mixed particles with either boson or fermion statistics. The mixing relations for quantum states are derived directly from the definition of mixing for quantum fields and the unitary inequivalence of the Fock space of energy and flavor eigenstates is shown by a straightforward algebraic method. The time dynamics of the interacting fields is then explicitly solved and the flavor oscillation formulas are derived in a unified general formulation with emphasis on antiparticle content and effect introduced by nontrivial flavor vacuum.}, number={3}, journal={UNIVERSE}, author={Ji, Chueng-Ryong and Mishchenko, Yuriy}, year={2021}, month={Mar} }
@article{barry_ji_sato_melnitchouk_2021, title={Global QCD Analysis of Pion Parton Distributions with Threshold Resummation}, volume={127}, ISSN={["1079-7114"]}, DOI={10.1103/PhysRevLett.127.232001}, abstractNote={We perform the first global QCD analysis of pion valence, sea quark, and gluon distributions within a Bayesian Monte Carlo framework with threshold resummation on Drell-Yan cross sections at next-to-leading log accuracy. Exploring various treatments of resummation, we find that the large-x asymptotics of the valence quark distribution ∼(1-x)^{β_{v}} can differ significantly, with β_{v} ranging from ≈1 to >2.5 at the input scale. Regardless of the specific implementation, however, the resummation induced redistribution of the momentum between valence quarks and gluons boosts the total momentum carried by gluons to ≈40%, increasing the gluon contribution to the pion mass to ≈40 MeV.}, number={23}, journal={PHYSICAL REVIEW LETTERS}, author={Barry, P. C. and Ji, Chueng-Ryong and Sato, N. and Melnitchouk, W.}, year={2021}, month={Nov} }
@article{ma_ji_2021, title={Interpolating 't Hooft model between instant and front forms}, volume={104}, ISSN={["2470-0029"]}, DOI={10.1103/PhysRevD.104.036004}, abstractNote={The 't Hooft model, i.e., the two-dimensional quantum chromodynamics in the limit of infinite number of colors, is interpolated by an angle parameter $\ensuremath{\delta}$ between $\ensuremath{\delta}=0$ for the instant form dynamics (IFD) and $\ensuremath{\delta}=\ensuremath{\pi}/4$ for the light-front dynamics (LFD). With this parameter $\ensuremath{\delta}$, we formulate the interpolating mass gap equation which takes into account the nontrivial vacuum effect on the bare fermion mass to find the dressed fermion mass. Our interpolating mass gap solutions not only reproduce the previous IFD result at $\ensuremath{\delta}=0$ as well as the previous LFD result at $\ensuremath{\delta}=\ensuremath{\pi}/4$ but also link them together between the IFD and LFD results with the $\ensuremath{\delta}$ parameter. We find the interpolation angle independent characteristic energy function which satisfies the energy-momentum dispersion relation of the dressed fermion, identifying the renormalized fermion mass function and the wave function renormalization factor. The renormalized fermion condensate is also found independent of $\ensuremath{\delta}$, indicating the persistence of the nontrivial vacuum structure even in the LFD. Using the dressed fermion propagator interpolating between IFD and LFD, we derive the corresponding quark-antiquark bound-state equation in the interpolating formulation verifying its agreement with the previous bound-state equations in the IFD and LFD at $\ensuremath{\delta}=0$ and $\ensuremath{\delta}=\ensuremath{\pi}/4$, respectively. The mass spectra of mesons bearing the feature of the Regge trajectories are found independent of the $\ensuremath{\delta}$-parameter reproducing the previous results in LFD and IFD for the equal mass quark and antiquark bound states. The Gell-Mann-Oakes-Renner relation for the pionic ground-state in the zero fermion mass limit is confirmed indicating that the spontaneous breaking of the chiral symmetry occurs in the 't Hooft model regardless of the quantization for $0\ensuremath{\le}\ensuremath{\delta}\ensuremath{\le}\ensuremath{\pi}/4$. We obtain the corresponding bound-state wave functions and discuss their reference frame dependence with respect to the frame independent LFD result. Applying them for the computation of the so-called quasi-parton distribution functions now in the interpolating formulation between IFD and LFD, we note a possibility of utilizing not only the reference frame dependence but also the interpolation angle dependence to get an alternative effective approach to the LFD-like results.}, number={3}, journal={PHYSICAL REVIEW D}, author={Ma, Bailing and Ji, Chueng-Ryong}, year={2021}, month={Aug} }
@article{choi_choi_ji_oh_2021, title={Light-front dynamic analysis of the longitudinal charge density using the solvable scalar field model in (1+1) dimensions}, volume={103}, ISSN={["2470-0029"]}, DOI={10.1103/PhysRevD.103.076002}, abstractNote={We investigate the electromagnetic form factor $F({q}^{2})$ of the meson by using the solvable ${\ensuremath{\phi}}^{3}$ scalar field model in ($1+1$) dimensions. As the transverse rotations are absent in ($1+1$) dimensions, the advantage of the light-front dynamics (LFD) with the light-front time ${x}^{+}={x}^{0}+{x}^{3}$ as the evolution parameter is maximized in contrast to the usual instant form dynamics (IFD) with the ordinary time ${x}^{0}$ as the evolution parameter. In LFD, the individual ${x}^{+}$-ordered amplitudes contributing to $F({q}^{2})$ are invariant under the boost, i.e., frame independent, while the individual ${x}^{0}$-ordered amplitudes in IFD are not invariant under the boost but dependent on the reference frame. The LFD allows us to get the analytic result for the one-loop triangle diagram which covers not only the spacelike (${q}^{2}<0$) but also timelike (${q}^{2}>0$) region. Using the analytic results, we verify that the real and imaginary parts of the form factor satisfy the dispersion relations in the entire ${q}^{2}$ space. Comparing with the results in ($3+1$) dimensions, we discuss the transverse momentum effects on $F({q}^{2})$. We also discuss the longitudinal charge density in terms of the boost-invariant variable $\stackrel{\texttildelow{}}{z}={p}^{+}{x}^{\ensuremath{-}}$ in LFD.}, number={7}, journal={PHYSICAL REVIEW D}, author={Choi, Yongwoo and Choi, Ho-Meoyng and Ji, Chueng-Ryong and Oh, Yongseok}, year={2021}, month={Apr} }
@article{copeland_ji_melnitchouk_2021, title={Octet and decuplet baryon self-energies in relativistic SU(3) chiral effective theory}, volume={103}, ISSN={["2470-0029"]}, DOI={10.1103/PhysRevD.103.094019}, abstractNote={The self-energies of the full set of flavor SU(3) octet and decuplet baryons are computed within a relativistic chiral effective theory framework. The leading nonanalytic chiral behavior is derived for the octet and decuplet masses, and a finite-range regularization consistent with Lorentz and gauge invariance is applied to account for the finite size of the baryons. Using a four-dimensional dipole form factor, the relative importance of various meson-baryon loop contributions to the self-energies is studied numerically as a function of the dipole range parameter and meson mass, and a comparison is made between the relativistic results and earlier approximations within the heavy baryon limit.}, number={9}, journal={PHYSICAL REVIEW D}, author={Copeland, P. M. and Ji, Chueng-Ryong and Melnitchouk, W.}, year={2021}, month={May} }
@article{choi_ji_2020, title={Chiral anomaly and the pion properties in the light-front quark model}, volume={102}, ISSN={["1550-2368"]}, DOI={10.1103/PhysRevD.102.036005}, abstractNote={We explore the link between the chiral symmetry of QCD and the numerical results of the light-front quark model, analyzing both the two-point and three-point functions of the pion. Including the axial-vector coupling as well as the pseudoscalar coupling in the light-front quark model, we discuss the implication of the chiral anomaly in describing the pion decay constant, the pion-photon transition form factor and the electromagnetic form factor of the pion. In constraining the model parameters, we find that the chiral anomaly plays a critical role and the analysis of ${F}_{\ensuremath{\pi}\ensuremath{\gamma}}({Q}^{2})$ in timelike region is important. Our results indicate that the constituent quark picture is effective for the low and high ${Q}^{2}$ ranges implementing the quark mass evolution effect as ${Q}^{2}$ grows.}, number={3}, journal={PHYSICAL REVIEW D}, author={Choi, Ho-Meoyng and Ji, Chueng-Ryong}, year={2020}, month={Aug} }
@article{ma_ji_2020, title={Interpolating QCD(2) between the Instant and Front Forms of Relativistic Dynamics}, volume={2249}, ISSN={["0094-243X"]}, DOI={10.1063/5.0008605}, abstractNote={The two-dimensional quantum chromodynamics (QCD2) in the limit of infinite number of colors, known as ‘t Hooft model, was originally formulated in the Light Front Dynamics (LFD). The theory is exactly solvable, while still bearing some resemblance to the four-dimensional real world QCD in aspects such as confinement and mass g ap, as well as the spontaneous breaking of chiral symmetry. The work in the Instant Form Dynamics (IFD) was done in 1978 by Bars and Green. The quark- antiquark bound state equation was derived and solved in each of the two forms, i.e., ‘t Hooft equation and Bars-Green equations, respectively, and they give the same discrete meson mass spectrum independent of the quantization form as expected. Introducing an interpolation angle parameter δ, in this work, we link the two distinct forms of dynamics, IFD and LFD, by letting the space-time axes rotate from the ordinary equal-time form {t, x} to the light front{x+,x−}, as δ varies from 0 to π/4. We unify the ‘t Hooft and Bars-Green equations into one formula, and by numerically solving it we confirm the independence of the meson mass spectra on the interpolation angle δ. We note that the quark condensate is quantization angle independent. This indicates a non-trivial vacuum structure even in the light-front form.}, journal={PROCEEDINGS OF THE 15TH INTERNATIONAL CONFERENCE ON MESON-NUCLEON PHYSICS AND THE STRUCTURE OF THE NUCLEON}, author={Ma, Bailing and Ji, Chueng-Ryong}, year={2020} }
@article{wang_ji_melnitchouk_salamu_thomas_wang_2020, title={Strange quark helicity in the proton from chiral effective theory}, volume={102}, ISSN={["2470-0029"]}, DOI={10.1103/PhysRevD.102.116020}, abstractNote={We compute the helicity-dependent strange quark distribution in the proton in the framework of chiral effective theory. Starting from the most general chiral SU(3) Lagrangian that respects Lorentz and gauge invariance, we derive the complete set of hadronic splitting functions at the one meson loop level, including the octet and decuplet rainbow, tadpole, Kroll-Ruderman and octet-decuplet transition configurations. By matching hadronic and quark level operators, we obtain generalized convolution formulas for the quark distributions in the proton in terms of hadronic splitting functions and quark distributions in the hadronic configurations, and from these derive model-independent relations for the leading nonanalytic behavior of their moments. Within the limits of parameters of the Pauli-Villars regulators derived from inclusive hyperon production, we find that the polarized strange quark distribution is rather small and mostly negative.}, number={11}, journal={PHYSICAL REVIEW D}, author={Wang, X. G. and Ji, Chueng-Ryong and Melnitchouk, W. and Salamu, Y. and Thomas, A. W. and Wang, P.}, year={2020}, month={Dec} }
@article{paula_ji_melo_frederico_lourenco_2020, title={The holographic paradigm of hadron dynamics for medium modified nuclear matters}, volume={803}, ISSN={["1873-2445"]}, DOI={10.1016/j.physletb.2020.135339}, abstractNote={We propose a medium-modified holographic-hadron dynamics suitable for the study of symmetric nuclear matter, with a key property of a simple law for the evolution of the five dimensional mass with the scalar background field. We show that the model satisfies symmetric nuclear matter constraints, namely, incompressibility and density dependence of the pressure, with only three free adjustable parameters fitted to the free nucleon mass and the nuclear matter saturation properties. We found that the holographic nucleon swells and the UV behavior of the associated string amplitude is damped, with the scaling property at short distances softened. Both effects can also generate observable consequences reflecting an average leakage of partons to the nuclear medium when density is increased, in the route towards the deconfinement of the internal nucleon degrees of freedom.}, journal={PHYSICS LETTERS B}, author={Paula, W. and Ji, Chueng-Ryong and Melo, J. P. B. C. and Frederico, T. and Lourenco, O.}, year={2020}, month={Apr} }
@article{ji_choi_lundeen_bakker_2019, title={Beam spin asymmetry in the electroproduction of a pseudoscalar meson or a scalar meson off the scalar target}, volume={99}, ISSN={["2470-0029"]}, DOI={10.1103/PhysRevD.99.116008}, abstractNote={We discuss the electroproduction of a pseudoscalar (${0}^{\ensuremath{-}+}$) meson or a scalar (${0}^{++}$) meson off the scalar target. The most general formulation of the differential cross section for the ${0}^{\ensuremath{-}+}$ or ${0}^{++}$ meson process involves only one or two hadronic form factors, respectively, on a scalar target. The Rosenbluth-type separation of the differential cross section provides the explicit relation between the hadronic form factors and the different parts of the differential cross section in a completely model-independent manner. The absence of the beam spin asymmetry for the pseudoscalar meson production provides a benchmark for the experimental data analysis. The measurement of the beam spin asymmetry for the scalar meson production may also provide a unique opportunity not only to explore the imaginary part of the hadronic amplitude in the general formulation but also to examine the significance of the chiral-odd generalized parton distribution (GPD) contribution in the leading-twist GPD formulation.}, number={11}, journal={PHYSICAL REVIEW D}, author={Ji, Chueng-Ryong and Choi, Ho-Meoyng and Lundeen, Andrew and Bakker, Bernard L. G.}, year={2019}, month={Jun} }
@article{choi_ryu_ji_2019, title={Doubly virtual (pi(0),eta,eta ') -> gamma*gamma* transition form factors in the light-front quark model}, volume={99}, ISSN={["2470-0029"]}, DOI={10.1103/PhysRevD.99.076012}, abstractNote={We report our investigation on the doubly virtual transition form factors (TFFs) ${F}_{\mathrm{P}{\ensuremath{\gamma}}^{*}}({Q}_{1}^{2},{Q}_{2}^{2})$ for the $\mathrm{P}\ensuremath{\rightarrow}{\ensuremath{\gamma}}^{*}({q}_{1}){\ensuremath{\gamma}}^{*}({q}_{2})(\mathrm{P}={\ensuremath{\pi}}^{0},\ensuremath{\eta},{\ensuremath{\eta}}^{\ensuremath{'}})$ transitions using the light-front quark model (LFQM). Performing a LF calculation in the exactly solvable manifestly covariant Bethe-Salpeter (BS) model as the first illustration, we use the ${q}_{1}^{+}=0$ frame and find that both LF and manifestly covariant calculations produce exactly the same results for ${F}_{\mathrm{P}{\ensuremath{\gamma}}^{*}}({Q}_{1}^{2},{Q}_{2}^{2})$. This confirms the absence of the LF zero mode in the doubly virtual TFFs. We then map this covariant BS model to the standard LFQM using the more phenomenologically accessible Gaussian wave function provided by the LFQM analysis of meson mass spectra. For the numerical analyses of ${F}_{\mathrm{P}{\ensuremath{\gamma}}^{*}}({Q}_{1}^{2},{Q}_{2}^{2})$, we compare our LFQM results with the available experimental data and the perturbative QCD (pQCD) and vector meson dominance (VMD) model predictions. As $({Q}_{1}^{2},{Q}_{2}^{2})\ensuremath{\rightarrow}\ensuremath{\infty}$, our LFQM result for doubly virtual TFF is consistent with the pQCD prediction, i.e., ${F}_{\mathrm{P}{\ensuremath{\gamma}}^{*}}({Q}_{1}^{2},{Q}_{2}^{2})\ensuremath{\sim}1/({Q}_{1}^{2}+{Q}_{2}^{2})$, while it differs greatly from the result of the VMD model, which behaves as ${F}_{\mathrm{P}{\ensuremath{\gamma}}^{*}}^{\mathrm{VMD}}({Q}_{1}^{2},{Q}_{2}^{2})\ensuremath{\sim}1/({Q}_{1}^{2}{Q}_{2}^{2})$. Our LFQM prediction for ${F}_{{\ensuremath{\eta}}^{\ensuremath{'}}{\ensuremath{\gamma}}^{*}}({Q}_{1}^{2},{Q}_{2}^{2})$ shows an agreement with the very recent experimental data obtained from the BABAR Collaboration for the ranges of $2<({Q}_{1}^{2},{Q}_{2}^{2})<60\text{ }\text{ }{\mathrm{GeV}}^{2}$.}, number={7}, journal={PHYSICAL REVIEW D}, author={Choi, Ho-Meoyng and Ryu, Hui-Young and Ji, Chueng-Ryong}, year={2019}, month={Apr} }
@article{salamu_ji_melnitchouk_thomas_wang_wang_2019, title={Parton distributions from nonlocal chiral SU(3) effective theory: Flavor asymmetries}, volume={100}, ISSN={["2470-0029"]}, DOI={10.1103/PhysRevD.100.094026}, abstractNote={Using recently derived results for one-loop hadronic splitting functions from a nonlocal implementation of chiral effective theory, we study the contributions from pseudoscalar meson loops to flavor asymmetries in the proton. Constraining the parameters of the regulating functions by inclusive production of $n$, ${\mathrm{\ensuremath{\Delta}}}^{++}$, $\mathrm{\ensuremath{\Lambda}}$, and ${\mathrm{\ensuremath{\Sigma}}}^{*+}$ baryons in $pp$ collisions, we compute the shape of the light antiquark asymmetry $\overline{d}\ensuremath{-}\overline{u}$ in the proton and the strange asymmetry $s\ensuremath{-}\overline{s}$ in the nucleon sea. With these constraints, the magnitude of the $\overline{d}\ensuremath{-}\overline{u}$ asymmetry is found to be compatible with that extracted from the Fermilab E866 Drell-Yan measurement, with no indication of a sign change at large values of $x$, and an integrated value in the range $⟨\overline{d}\ensuremath{-}\overline{u}⟩\ensuremath{\approx}0.09--0.17$. The $s\ensuremath{-}\overline{s}$ asymmetry is predicted to be positive at $x>0$, with compensating negative contributions at $x=0$, and an integrated $x$-weighted moment in the range $⟨x(s\ensuremath{-}\overline{s})⟩\ensuremath{\approx}(0.9\ensuremath{-}2.5)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$.}, number={9}, journal={PHYSICAL REVIEW D}, author={Salamu, Y. and Ji, Chueng-Ryong and Melnitchouk, W. and Thomas, A. W. and Wang, P. and Wang, X. G.}, year={2019}, month={Nov} }
@article{salamu_ji_melnitchouk_thomas_wang_2019, title={Parton distributions from nonlocal chiral SU(3) effective theory: Splitting functions}, volume={99}, ISSN={["2470-0029"]}, DOI={10.1103/PhysRevD.99.014041}, abstractNote={We present a new formulation of pseudoscalar meson loop corrections to nucleon parton distributions within a nonlocal covariant chiral effective field theory, including contributions from SU(3) octet and decuplet baryons. The nonlocal Lagrangian, constrained by requirements of local gauge invariance and Lorentz-invariant ultraviolet regularization, generates additional interactions associated with gauge links. We use these to compute the full set of $\mathrm{proton}\ensuremath{\rightarrow}\mathrm{meson}+\mathrm{baryon}$ splitting functions, which in general contain on-shell and off-shell contributions, in addition to $\ensuremath{\delta}$-function terms at zero momentum, along with nonlocal contributions associated with the finite size of the proton. We illustrate the shapes of the various local and nonlocal functions numerically using a simple example of a dipole regulator.}, number={1}, journal={PHYSICAL REVIEW D}, author={Salamu, Y. and Ji, Chueng-Ryong and Melnitchouk, W. and Thomas, A. W. and Wang, P.}, year={2019}, month={Jan} }
@article{ji_suzuki_sales_thibes_2019, title={Pauli-Villars regularization elucidated in Bopp-Podolsky's generalized electrodynamics}, volume={79}, ISSN={["1434-6052"]}, DOI={10.1140/epjc/s10052-019-7384-1}, abstractNote={Abstract We discuss an inherent Pauli–Villars regularization in Bopp–Podolsky’s generalized electrodynamics. Introducing gauge-fixing terms for Bopp–Podolsky’s generalized electrodynamic action, we realize a unique feature for the corresponding photon propagator with a built-in Pauli–Villars regularization independent of the gauge choice made in Maxwell’s usual electromagnetism. According to our realization, the length dimensional parameter a associated with Bopp–Podolsky’s higher order derivatives corresponds to the inverse of the Pauli–Villars regularization mass scale $$\Lambda $$ Λ , i.e. $$a = 1/\Lambda $$ a=1/Λ . Solving explicitly the classical static Bopp–Podolsky’s equations of motion for a specific charge distribution, we explore the physical meaning of the parameter a in terms of the size of the charge distribution. As an offspring of the generalized photon propagator analysis, we also discuss our findings regarding on the issue of the two-term vs. three-term photon propagator in light-front dynamics.}, number={10}, journal={EUROPEAN PHYSICAL JOURNAL C}, author={Ji, Chueng-Ryong and Suzuki, Alfredo Takashi and Sales, Jorge Henrique and Thibes, Ronaldo}, year={2019}, month={Oct} }
@article{choi_frederico_ji_melo_2019, title={Pion off-shell electromagnetic form factors: Data extraction and model analysis}, volume={100}, ISSN={["2470-0029"]}, DOI={10.1103/PhysRevD.100.116020}, abstractNote={We investigate the pion electromagnetic half off-shell form factors, which parametrize the matrix element of the charged pion electromagnetic current with one leg off-mass-shell and the other leg on-mass-shell, using an exactly solvable manifestly covariant model of a $(3+1)$ dimensional fermion field theory. The model provides a 3D imaging of the two off-shell pion form factors $F_1$ and $F_2$ as a function of $(Q^2,t)$, which are related to each other satisfying the Ward-Takahashi identity. The normalization of the renormalized charge form factor $F_1$ is fixed by $F_1(Q^2=0, t=m^2_\pi)=1$ while the other form factor $F_2$ vanishes, i.e. $F_2(Q^2, t=m^2_\pi)=0$ for any value of $Q^2$ due to the time-reversal invariance of the strong interaction. We define the new form factor $g(Q^2,t)=F_2(Q^2,t)/(t-m^2_\pi)$ and find that $g(Q^2,t)$ can be measurable in the on-mass-shell limit. In particular, $g(Q^2=0, t=m^2_\pi)$ is related with the pion charge radius. We also compare our form factors with the data extracted from the pion electroproduction reaction for both the off-shell region ($t<0$) and the on-shell limit ($t \rightarrow m_\pi^2$).}, number={11}, journal={PHYSICAL REVIEW D}, author={Choi, Ho-Meoyng and Frederico, T. and Ji, Chueng-Ryong and Melo, J. P. B. C.}, year={2019}, month={Dec} }
@article{bakker_ji_2019, title={The Compton Form Factors of the (4)Helium Nucleus}, volume={60}, ISSN={["1432-5411"]}, DOI={10.1007/s00601-019-1509-9}, abstractNote={The number of Compton form factors of a scalar hadron is known to be three. It may be expected that depending on the structure of that hadron, it may occur that in some kinematical regimes the observables are only sensitive to one dominant form factor. Here we show in a particular kinematic situation that one may perform an experiment that unequivocally answers the question whether other form factors besides the anticipated dominant one can be neglected or not.}, number={2}, journal={FEW-BODY SYSTEMS}, author={Bakker, Bernard L. G. and Ji, Chueng-Ryong}, year={2019}, month={Jun} }
@article{dhiman_dahiya_ji_choi_2019, title={Twist-2 pseudoscalar and vector meson distribution amplitudes in light-front quark model with exponential-type confining potential}, volume={100}, ISSN={["2470-0029"]}, DOI={10.1103/PhysRevD.100.014026}, abstractNote={We study the twist-2 distribution amplitudes (DAs) and the decay constants of pseudoscalar light ($\ensuremath{\pi}$, $K$) and heavy ($D$, ${D}_{s}$, $B$, ${B}_{s}$) mesons as well as the longitudinally and transversely polarized vector light ($\ensuremath{\rho}$, ${K}^{*}$) and heavy (${D}^{*}$, ${D}_{s}^{*}$, ${B}^{*}$, ${B}_{s}^{*}$) mesons in the light-front quark model with the Coulomb plus exponential-type confining potential ${V}_{\mathrm{exp}}=a+b{e}^{\ensuremath{\alpha}r}$ in addition to the hyperfine interaction. We first compute the mass spectra of ground state pseudoscalar and vector light and heavy mesons and fix the model parameters necessary for the analysis, applying the variational principle with the trial wave function up to the first three lowest order harmonic oscillator (HO) wave functions $\mathrm{\ensuremath{\Phi}}(x,{\mathbf{k}}_{\ensuremath{\perp}})=\ensuremath{\sum}_{n=1}^{3}{c}_{n}{\ensuremath{\phi}}_{nS}$. We then obtain the numerical results for the corresponding decay constants of light and heavy mesons. We estimate the DAs, analyze their variation as a function of momentum fraction and compute the first six $\ensuremath{\xi}$-moments of the $B$ and $D$ mesons as well. We compare our results with the available experimental data as well as with the other theoretical model predictions.}, number={1}, journal={PHYSICAL REVIEW D}, author={Dhiman, Nisha and Dahiya, Harleen and Ji, Chueng-Ryong and Choi, Ho-Meoyng}, year={2019}, month={Jul} }
@article{alvarenga nogueira_ji_ydrefors_frederico_2018, title={Color-suppression of non-planar diagrams in bosonic bound states}, volume={777}, ISSN={["1873-2445"]}, DOI={10.1016/j.physletb.2017.12.032}, abstractNote={We study the suppression of non-planar diagrams in a scalar QCD model of a meson system in 3+1 space–time dimensions due to the inclusion of the color degrees of freedom. As a prototype of the color-singlet meson, we consider a flavor-nonsinglet system consisting of a scalar-quark and a scalar-antiquark with equal masses exchanging a scalar-gluon of a different mass, which is investigated within the framework of the homogeneous Bethe–Salpeter equation. The equation is solved by using the Nakanishi representation for the manifestly covariant bound-state amplitude and its light-front projection. The resulting non-singular integral equation is solved numerically. The damping of the impact of the cross-ladder kernel on the binding energies are studied in detail. The color-suppression of the cross-ladder effects on the light-front wave function and the elastic electromagnetic form factor are also discussed. As our results show, the suppression appears significantly large for Nc=3, which supports the use of rainbow-ladder truncations in practical non-perturbative calculations within QCD.}, journal={PHYSICS LETTERS B}, author={Alvarenga Nogueira, J. H. and Ji, Chueng-Ryong and Ydrefors, E. and Frederico, T.}, year={2018}, month={Feb}, pages={207–211} }
@article{barry_sato_melnitchouk_ji_2018, title={First Monte Carlo Global QCD Analysis of Pion Parton Distributions}, volume={121}, ISSN={["1079-7114"]}, DOI={10.1103/PhysRevLett.121.152001}, abstractNote={We perform the first global QCD analysis of parton distribution functions (PDFs) in the pion, combining πA Drell-Yan data with leading neutron electroproduction from HERA within a Monte Carlo approach based on nested sampling. Inclusion of the HERA data allows the pion PDFs to be determined down to much lower values of x, with relatively weak model dependence from uncertainties in the chiral splitting function. The combined analysis reveals that gluons carry a significantly higher pion momentum fraction, ∼30%, than that inferred from Drell-Yan data alone, with sea quarks carrying a somewhat smaller fraction, ∼15%, at the input scale. Within the same effective theory framework, the chiral splitting function and pion PDFs can be used to describe the d[over ¯]-u[over ¯] asymmetry in the proton.}, number={15}, journal={PHYSICAL REVIEW LETTERS}, author={Barry, P. C. and Sato, N. and Melnitchouk, W. and Ji, Chueng-Ryong}, year={2018}, month={Oct} }
@article{ji_li_ma_suzuki_2018, title={Interpolating Quantum Electrodynamics}, volume={59}, ISSN={["1432-5411"]}, DOI={10.1007/s00601-018-1397-4}, abstractNote={We discuss the interpolation between the instant form dynamics (IFD) and the light-front dynamics (LFD) proposed by Dirac in 1949 and present its application to quantum electrodynamics (QED). Our analysis clarifies any conceivable confusion in the prevailing notion of the equivalence between the IFD at infinite momentum frame and the LFD. Entwining the fermion propagator interpolation with our previous works of the interpolating helicity spinors and the electromagnetic gauge field interpolation, we fasten the bolts and nuts necessary to launch the interpolating QED at least in the tree level.}, number={5}, journal={FEW-BODY SYSTEMS}, author={Ji, Chueng-Ryong and Li, Ziyue and Ma, Bailing and Suzuki, Alfredo Takashi}, year={2018}, month={Sep} }
@article{ji_li_ma_suzuki_2018, title={Interpolating quantum electrodynamics between instant and front forms}, volume={98}, ISSN={["2470-0029"]}, DOI={10.1103/PhysRevD.98.036017}, abstractNote={The instant form and the front form of relativistic dynamics proposed by Dirac in 1949 can be linked by an interpolation angle parameter $\delta$ spanning between the instant form dynamics (IFD) at $\delta =0$ and the front form dynamics which is now known as the light-front dynamics (LFD) at $\delta =\pi/4$. We present the formal derivation of the interpolating quantum electrodynamics (QED) in the canonical field theory approach and discuss the constraint fermion degree of freedom which appears uniquely in the LFD. The constraint component of the fermion degrees of freedom in LFD results in the instantaneous contribution to the fermion propagator, which is genuinely distinguished from the ordinary equal-time forward and backward propagation of relativistic fermion degrees of freedom. As discussed in our previous work, the helicity of the on-mass-shell fermion spinors in LFD is also distinguished from the ordinary Jacob-Wick helicity in the IFD with respect to whether the helicity depends on the reference frame or not. To exemplify the characteristic difference of the fermion propagator between IFD and LFD, we compute the helicity amplitudes of typical QED processes such as $e^+ e^- \to \gamma \gamma$ and $e \gamma \to e \gamma$ and present the whole landscape of the scattering amplitudes in terms of the frame dependence or the scattering angle dependence with respect to the interpolating angle dependence. Our analysis clarifies any conceivable confusion in the prevailing notion of the equivalence between the infinite momentum frame approach and the LFD.}, number={3}, journal={PHYSICAL REVIEW D}, author={Ji, Chueng-Ryong and Li, Ziyue and Ma, Bailing and Suzuki, Alfredo Takashi}, year={2018}, month={Aug} }
@article{melo_frederico_ji_2018, title={Spin-1 Particles and Perturbative QCD}, volume={59}, ISSN={["1432-5411"]}, DOI={10.1007/s00601-018-1383-x}, abstractNote={Due to the angular condition in the light-front dynamics (LFD), the extraction of the electromagnetic form factors for spin-1 particles can be uniquely determined taking into account implicitly non-valence and/or the zero-mode contributions to the matrix elements of the electromagnetic current. No matter which matrix elements of the electromagnetic current is used to extract the electromagnetic form factors, the same unique result is obtained. As physical observables, the electromagnetic form factors obtained from matrix elements of the current in LFD must be equal to those obtained in the instant form calculations. Recently, the Babar collaboration \cite{Aubert2008} has analyzed the reaction $e^+ e^-\rightarrow \rho^+ + \rho^-$ at $\sqrt{s}=10.58 GeV$ to measure the cross section as well as the ratios of the helicity amplitudes $F_{\lambda'\lambda}$. We present our recent analysis of the Babar data for the rho meson considering the angular condition in LFD to put a stringent test on the onset of asymptotic perturbative QCD and predict the energy regime where the subleading contributions are still considerable.}, number={4}, journal={FEW-BODY SYSTEMS}, author={Melo, J. P. B. C. and Frederico, T. and Ji, Chueng-Ryong}, year={2018}, month={Jul} }
@article{corey_thompson_hittle_jacobs_asafo-adjei_huggins_melander_melander_ernst_zurawski_et al._2017, title={1,2,4-Triazolidine-3-thiones Have Specific Activity against Acinetobacter baumannii among Common Nosocomial Pathogens}, volume={3}, ISSN={["2373-8227"]}, DOI={10.1021/acsinfecdis.6b00133}, abstractNote={Acinetobacter baumannii are Gram-negative bacilli that pose a constant threat to susceptible patients because of increased resistance to multiple antibiotics and persistence in the hospital environment. After genome analysis, we discovered that A. baumannii harbors genes that share homology to an enzymatic pathway that elongates long-chain fatty acids (LCFA) in fungi. Previously, 1,2,4-triazolidine-3-thiones (T-3-Ts) were shown to inhibit hyphae production in fungi, and this same LCFA elongation pathway was implicated as the possible target. Therefore, we investigated if T-3-Ts also have activity against multidrug-resistant A. baumannii. Surprisingly, all of the clinical isolates of A. baumannii that were tested have susceptibility to ECC145 and ECC188 with MIC90 values of 8.0 μg/mL. In contrast, reference strains and clinical isolates of other common nosocomial bacteria that lack the LCFA pathway also lacked susceptibility. Time–kill experiments revealed that both ECC145 and ECC188 have a bacteriostatic effect against A. baumannii. Mass spectrometry analysis suggested that exposure to T-3-Ts resulted in less LCFA production. Supplementation of media with either 0.02% w/v oleic or linoleic acid abrogated the bacteriostatic effect of the compounds, which again implicated LCFA elongation as the target. Our results suggest these molecules could be a promising start to further exploit what appears to be an important aspect of A. baumannii membrane function and integrity.}, number={1}, journal={ACS INFECTIOUS DISEASES}, author={Corey, B. W. and Thompson, M. G. and Hittle, L. E. and Jacobs, A. C. and Asafo-Adjei, E. A. and Huggins, W. M. and Melander, R. J. and Melander, C. and Ernst, R. K. and Zurawski, D. V. and et al.}, year={2017}, month={Jan}, pages={62–71} }
@article{burchhardt_miller_cline_cubeta_2017, title={Fine-Scale Genetic Structure and Reproductive Biology of the Blueberry Pathogen Monilinia vaccinii-corymbosi}, volume={107}, ISSN={0031-949X}, url={http://dx.doi.org/10.1094/PHYTO-02-16-0093-R}, DOI={10.1094/phyto-02-16-0093-r}, abstractNote={The fungus Monilinia vaccinii-corymbosi, a pathogen of Vaccinium spp., requires asexual and sexual spore production to complete its life cycle. A recent study found population structuring of M. vaccinii-corymbosi over a broad spatial scale in the United States. In this study, we examined fine-scale genetic structuring, temporal dynamics, and reproductive biology within a 125-by-132-m blueberry plot from 2010 to 2012. In total, 395 isolates of M. vaccinii-corymbosi were sampled from infected shoots and fruit to examine their multilocus haplotype (MLH) using microsatellite markers. The MLH of 190 single-ascospore isolates from 21 apothecia was also determined. Little to no genetic differentiation and unrestricted gene flow were detected among four sampled time points and between infected tissue types. Discriminant analysis of principal components suggested genetic structuring within the field, with at least K = 3 genetically distinct clusters maintained over four sampled time points. Single-ascospore progeny from eight apothecia had identical MLH and at least two distinct MLH were detected from 13 apothecia. Tests for linkage disequilibrium suggested that genetically diverse ascospore progeny were the product of recombination. This study supports the idea that the fine-scale dynamics of M. vaccinii-corymbosi may be complex, with genetic structuring, inbreeding, and outcrossing detected in the study area.}, number={2}, journal={Phytopathology}, publisher={Scientific Societies}, author={Burchhardt, Kathleen M. and Miller, Megan E. and Cline, William O. and Cubeta, Marc A.}, year={2017}, month={Feb}, pages={231–239} }
@article{ji_2017, title={Interpolation Between the Instant Form and the Front Form of Relativistic Dynamics}, volume={58}, ISSN={0177-7963 1432-5411}, url={http://dx.doi.org/10.1007/S00601-016-1209-7}, DOI={10.1007/S00601-016-1209-7}, number={2}, journal={Few-Body Systems}, publisher={Springer Nature}, author={Ji, Chueng-Ryong}, year={2017}, month={Jan} }
@article{ji_2017, title={Light-front field theory in the description of hadrons}, volume={137}, ISSN={2100-014X}, url={http://dx.doi.org/10.1051/EPJCONF/201713705008}, DOI={10.1051/EPJCONF/201713705008}, abstractNote={We discuss the use of light-front field theory in the descriptions of hadrons. In particular, we clarify the confusion in the prevailing notion of the equivalence between the infinite momentum frame and the light-front dynamics and the advantage of the light-front dynamics in hadron physics. As an application, we present our recent work on the flavor asymmetry in the proton sea and identify the presence of the delta-function contributions associated with end-point singularities arising from the chiral effective theory calculation. The results pave the way for phenomenological applications of pion cloud models that are manifestly consistent with the chiral symmetry properties of QCD.}, journal={EPJ Web of Conferences}, publisher={EDP Sciences}, author={Ji, Chueng-Ryong}, editor={Foka, Y. and Brambilla, N. and Kovalenko, V.Editors}, year={2017}, pages={05008} }
@inproceedings{ji_2017, title={Light-front field theory in the description of hadrons}, volume={137}, booktitle={Xiith quark confinement and the hadron spectrum}, author={Ji, C. R.}, year={2017} }
@article{kim_ji_2017, title={Matter equation of state in general relativity}, volume={95}, ISSN={["2470-0029"]}, DOI={10.1103/physrevd.95.084045}, abstractNote={We study how a strong gravity affects the equation of state of matter. For this purpose, we employ a canonical ensemble of classical monoatomic ideal gas inside a box in Rindler spacetime. The total energy decreases monotonically with the increase of the external gravity, representing its attractiveness. It is, however, bounded below, which is different from the Newtonian gravity case. As for the entropy, it decreases with the external gravity in the Newtonian regime. However, in the presence of strong gravity or ultrarelativistic high temperature, the entropy increases with the gravity. This result can be a resolution of the negative entropy problem of the ideal gas in Newtonian gravity. In the presence of strong gravity, the bottom of the box is very close to the event horizon of Rindler spacetime, mimicking a black hole, and the gas behaves as if it is on an effective two-dimensional surface located at the bottom of the box. Investigating the equation of state in the strong gravity regime, the temperature of the system is found to be not a free parameter but to approach a fixed value proportional to the external gravity, which is reminiscent of the Unruh temperature.}, number={8}, journal={PHYSICAL REVIEW D}, author={Kim, Hyeong-Chan and Ji, Chueng-Ryong}, year={2017}, month={Apr} }
@article{choi_ryu_ji_2017, title={Spacelike and timelike form factors for the (pi(0) ,eta,eta ') -> gamma*gamma transitionsin the light-front quark model}, volume={96}, ISSN={["2470-0029"]}, DOI={10.1103/physrevd.96.056008}, abstractNote={We investigate the $({\ensuremath{\pi}}^{0},\ensuremath{\eta},{\ensuremath{\eta}}^{\ensuremath{'}})\ensuremath{\rightarrow}{\ensuremath{\gamma}}^{*}\ensuremath{\gamma}$ transitions both for the spacelike region and the timelike region using the light-front quark model (LFQM). In particular, we present the new direct method to explore the timelike region without resorting to mere analytic continuation from the spacelike region to the timelike region. Our direct calculation in timelike region shows the complete agreement not only with the analytic continuation result from the spacelike region but also with the result from the dispersion relation between the real and imaginary parts of the form factor. For the low energy regime, we compare our LFQM results of the transition form factors (TFFs) for the low timelike momentum transfer region and the slope parameters at ${q}^{2}=0$ with the recent experimental data from the Dalitz decays of $({\ensuremath{\pi}}^{0},\ensuremath{\eta},{\ensuremath{\eta}}^{\ensuremath{'}})$. For the high energy regime, we incorporate the QCD factorization in our LFQM to examine the asymptotic behavior of TFFs both for the spacelike region and the timelike region. We compare our results with the available experimental data.}, number={5}, journal={PHYSICAL REVIEW D}, author={Choi, Ho-Meoyng and Ryu, Hui-Young and Ji, Chueng-Ryong}, year={2017}, month={Sep} }
@article{choi_ji_2017, title={Twist-3 Distribution Amplitudes of Pion in the Light-Front Quark Model}, volume={58}, ISSN={0177-7963 1432-5411}, url={http://dx.doi.org/10.1007/S00601-016-1208-8}, DOI={10.1007/S00601-016-1208-8}, abstractNote={We analyzed two twist-3 distribution amplitudes of pion, i.e. pseudoscalar $\phi^P_{3;\pi}(x)$ and pseudotensor $\phi^\sigma_{3;\pi}(x)$, within the LFQM. Our LFQM descriptions both for twist-3 $\phi^P_{3;\pi}$ and $\phi^\sigma_{3;\pi}$ not only satisfy the fundamental constraint required from the isospin symmetry, but also reproduce exactly the asymptotic forms anticipated from QCD's conformal limit.}, number={2}, journal={Few-Body Systems}, publisher={Springer Nature}, author={Choi, Ho-Meoyng and Ji, Chueng-Ryong}, year={2017}, month={Jan} }
@article{choi_ji_2017, title={Two-particle twist-3 distribution amplitudes of the pion and kaon in the light-front quark model}, volume={95}, ISSN={["2470-0029"]}, DOI={10.1103/physrevd.95.056002}, abstractNote={We investigate the two-particle twist-3 distribution amplitudes (DAs) of the pseudoscalar mesons, in particular pseudoscalar ($\phi^P_{3;M}(x)$) and pseudotensor ($\phi^\sigma_{3;M}(x)$) DAs of the pion and kaon, in the light-front quark model based on the variational principle. We find that the behavior of the conformal symmetry in each meson distribution amplitude depends on the chiral limit characteristics of the light-front trial wave function taken in the variational principle. We specifically take the two different light-front trial wave functions, Gaussian vs. power-law type, and discuss their characteristics of the conformal symmetry in the chiral symmetry limit as well as their resulting degree of the conformal symmetry breaking in $\phi^P_{3;M}(x)$ and $\phi^\sigma_{3;M}(x)$ depending on the trial wave function taken in the computation. We present numerical results of transverse moments, Gegenbauer-moments and $\xi$-moments and compare them with other available model estimates. The SU(3) flavor-symmetry breaking effect is also quantified with the numerical computation.}, number={5}, journal={PHYSICAL REVIEW D}, author={Choi, Ho-Meoyng and Ji, Chueng-Ryong}, year={2017}, month={Mar} }
@inproceedings{jiang_sung_song_ke_liu_baliga_huang_van brunt_2016, title={10kv sic mps diodes for high temperature applications}, booktitle={2016 28th international symposium on power semiconductor devices and ics (ispsd)}, author={Jiang, Y. F. and Sung, W. J. and Song, X. Q. and Ke, H. T. and Liu, S. Y. and Baliga, B. J. and Huang, A. Q. and Van Brunt, E.}, year={2016}, pages={43–46} }
@article{wang_ji_melnitchouk_salamu_thomas_wang_2016, title={Constraints on the s - (s)over-bar asymmetry of the proton in chiral effective theory}, volume={762}, ISSN={["1873-2445"]}, DOI={10.1016/j.physletb.2016.09.014}, abstractNote={We compute the $s-\bar s$ asymmetry in the proton in chiral effective theory, using phenomenological constraints based upon existing data. Unlike previous meson cloud model calculations, which accounted for kaon loop contributions with on-shell intermediate states alone, this work includes off-shell terms and contact interactions, which impact the shape of the $s-\bar s$ difference. We identify a valence-like component of $s(x)$ which is balanced by a $\delta$-function contribution to $\bar s(x)$ at $x=0$, so that the integrals of $s$ and $\bar s$ over the experimentally accessible region $x > 0$ are not equal. Using a regularization procedure that preserves chiral symmetry and Lorentz invariance, we find that existing data limit the integrated value of the second moment of the asymmetry to the range $-0.07 \times 10^{-3} \leq \langle x(s-\bar s) \rangle \leq 1.12 \times 10^{-3}$ at a scale of $Q^2=1 $GeV$^2$. This is too small to account for the NuTeV anomaly and of the wrong sign to enhance it.}, journal={PHYSICS LETTERS B}, author={Wang, X. G. and Ji, Chueng-Ryong and Melnitchouk, W. and Salamu, Y. and Thomas, A. W. and Wang, P.}, year={2016}, month={Nov}, pages={52–56} }
@article{choi_ji_2016, title={Light-Front Quark Model Analysis of Meson-Photon Transition Form Factor}, volume={57}, ISSN={["1432-5411"]}, DOI={10.1007/s00601-016-1053-9}, abstractNote={We discuss $${(\pi^{0}, \eta, \eta') \to \gamma^{*}\gamma}$$ transition form factors using the light-front quark model. Our discussion includes the analysis of the mixing angles for $${\eta-\eta'}$$ . Our results for $${Q^{2} F_{(\pi^0,\eta,\eta')\to\gamma^*\gamma}(Q^2)}$$ show scaling behavior for high Q 2 consistent with pQCD predictions.}, number={7}, journal={FEW-BODY SYSTEMS}, author={Choi, Ho-Meoyng and Ji, Chueng-Ryong}, year={2016}, month={Jul}, pages={497–501} }
@article{choi_ji_2016, title={Light-Front Quark Model Phenomenology Consistent with Chiral Symmetry}, volume={113}, ISSN={2100-014X}, url={http://dx.doi.org/10.1051/EPJCONF/201611305009}, DOI={10.1051/EPJCONF/201611305009}, abstractNote={We discuss the link between the chiral symmetry of QCD and the numerical results of the light-front quark model, analyzing both the twist-2 and twist-3 distribution amplitudes of a pion. In particular, we exhibit that the pion twist-3 distribution amplitude can flip the sign of curvature as the cutoff scale for the transverse momentum gets lower than a typical scale of around 1 GeV.}, journal={EPJ Web of Conferences}, publisher={EDP Sciences}, author={Choi, Ho-Meoyng and Ji, Chueng-Ryong}, editor={Elster, C. and Phillips, D.R. and Roberts, C.D.Editors}, year={2016}, pages={05009} }
@inproceedings{choi_ji_2016, title={Light-front quark model phenomenology consistent with chiral symmetry}, volume={113}, booktitle={21st international conference on few-body problems in physics}, author={Choi, H. M. and Ji, C. R.}, year={2016} }
@article{mckenney_sato_melnitchouk_ji_2016, title={Pion structure function from leading neutron electroproduction and SU(2) flavor asymmetry}, volume={93}, ISSN={["2470-0029"]}, DOI={10.1103/physrevd.93.054011}, abstractNote={We examine the efficacy of pion exchange models to simultaneously describe leading neutron electroproduction at HERA and the $\bar{d}-\bar{u}$ flavor asymmetry in the proton. A detailed $\chi^2$ analysis of the ZEUS and H1 cross sections, when combined with constraints on the pion flux from Drell-Yan data, allows regions of applicability of one-pion exchange to be delineated. The analysis disfavors several models of the pion flux used in the literature, and yields an improved extraction of the pion structure function and its uncertainties at parton momentum fractions in the pion of $4 \times 10^{-4} \lesssim x_\pi \lesssim 0.05$ at a scale of $Q^2$=10 GeV$^2$. Based on the fit results, we provide estimates for leading proton structure functions in upcoming tagged deep-inelastic scattering experiments at Jefferson Lab on the deuteron with forward protons.}, number={5}, journal={PHYSICAL REVIEW D}, author={McKenney, J. R. and Sato, Nobuo and Melnitchouk, W. and Ji, Chueng-Ryong}, year={2016}, month={Mar} }
@article{mckenney_sato_melnitchouk_ji_2016, title={SU(2) Flavor Asymmetry of the Proton Sea in Chiral Effective Theory}, volume={57}, ISSN={["1432-5411"]}, DOI={10.1007/s00601-016-1047-7}, number={7}, journal={FEW-BODY SYSTEMS}, author={McKenney, J. R. and Sato, Nobuo and Melnitchouk, W. and Ji, Chueng-Ryong}, year={2016}, month={Jul}, pages={593–599} }
@article{bakker_ji_2016, title={Sensitivity of the DVCS Cross Section to the Compton form Factors in Scalar QED}, volume={57}, ISSN={["1432-5411"]}, DOI={10.1007/s00601-016-1069-1}, abstractNote={Using deeply virtual Compton scattering as a tool to study the structure of hadrons in an exclusive process, one expresses the amplitudes in terms of invariant quantities: the Compton form factors. In this paper the sensitivity of the hadronic part of the cross section to the Compton form factors is determined.}, number={7}, journal={FEW-BODY SYSTEMS}, author={Bakker, Bernard L. G. and Ji, Chueng-Ryong}, year={2016}, month={Jul}, pages={579–584} }
@article{wang_ji_melnitchouk_salamu_thomas_wang_2016, title={Strange-quark asymmetry in the proton in chiral effective theory}, volume={94}, ISSN={["2470-0029"]}, DOI={10.1103/physrevd.94.094035}, abstractNote={We perform a comprehensive analysis of the strange-antistrange parton distribution function (PDF) asymmetry in the proton in the framework of chiral effective theory, including the full set of lowest order kaon loop diagrams with off-shell and contact interactions, in addition to the usual on-shell contributions previously discussed in the literature. We identify the presence of $\delta$-function contributions to the $\bar s$ PDF at $x=0$, with a corresponding valence-like component of the $s$-quark PDF at larger $x$, which allows greater flexibility for the shape of $s-\bar s$. Expanding the moments of the PDFs in terms of the pseudoscalar kaon mass, we compute the leading nonanalytic behavior of the number and momentum integrals of the $s$ and $\bar s$ distributions, consistent with the chiral symmetry of QCD. We discuss the implications of our results for the understanding of the NuTeV anomaly and for the phenomenology of strange quark PDFs in global QCD analysis.}, number={9}, journal={PHYSICAL REVIEW D}, author={Wang, X. G. and Ji, Chueng-Ryong and Melnitchouk, W. and Salamu, Y. and Thomas, A. W. and Wang, P.}, year={2016}, month={Nov} }
@article{bakker_ji_2016, title={The Construction of Compton Tensors in Scalar QED}, volume={58}, ISSN={0177-7963 1432-5411}, url={http://dx.doi.org/10.1007/S00601-016-1172-3}, DOI={10.1007/S00601-016-1172-3}, abstractNote={Current conservation is a vital condition in electrodynamics. We review the literature concerning the ways to ensure that the formalism used in calculating amplitudes for the scattering of charged particles is in compliance with current conservation. For the case of electron scattering off a scalar and a spin-1/2 target as well as Compton scattering on a scalar target, we present some novelties besides reviewing the literature.}, number={1}, journal={Few-Body Systems}, publisher={Springer Nature}, author={Bakker, Bernard L. G. and Ji, Chueng-Ryong}, year={2016}, month={Dec} }
@article{melo_ji_frederico_2016, title={The rho-meson time-like form factors in sub-leading pQCD}, volume={763}, ISSN={["1873-2445"]}, DOI={10.1016/j.physletb.2016.10.018}, abstractNote={The annihilation/production process e++e−→ρ++ρ− is studied with respect to the universal perturbative QCD (pQCD) predictions. Sub-leading contributions are considered together with the universal leading pQCD amplitudes such that the matrix elements of the ρ-meson electromagnetic current satisfy the constraint from the light-front angular condition. The data from the BaBar collaboration for the time-like ρ-meson form factors at s=10.58GeV puts a stringent test to the onset of asymptotic pQCD behavior. The e++e−→ρ++ρ− cross-section for s between 60GeV2 and 160GeV2 is predicted where the sub-leading contributions are still considerable.}, journal={PHYSICS LETTERS B}, author={Melo, J. P. B. C. and Ji, Chueng-Ryong and Frederico, T.}, year={2016}, month={Dec}, pages={87–93} }
@article{salamu_ji_melnitchouk_wang_2015, title={(d)over-bar - (u)over-bar Asymmetry in the Proton in Chiral Effective Theory}, volume={114}, ISSN={["1079-7114"]}, DOI={10.1103/physrevlett.114.122001}, abstractNote={We compute the d[over ¯]-u[over ¯] asymmetry in the proton in chiral effective theory, including both nucleon and Δ degrees of freedom, within the relativistic and heavy baryon frameworks. In addition to the distribution at x>0, we compute the corrections to the asymmetry from zero momentum contributions from pion rainbow and bubble diagrams at x=0, which have not been accounted for in previous analyses. We find that the empirical x dependence of d[over ¯]-u[over ¯] as well as the integrated asymmetry can be well reproduced in terms of a transverse momentum cutoff parameter.}, number={12}, journal={PHYSICAL REVIEW LETTERS}, author={Salamu, Yusupujiang and Ji, Chueng-Ryong and Melnitchouk, W. and Wang, P.}, year={2015}, month={Mar} }
@article{salamu_ji_melnitchouk_wang_2015, title={(d)over-bar - (u)over-bar Flavor Asymmetry in the Proton in Chiral Effective Field Theory}, volume={56}, ISSN={["1432-5411"]}, DOI={10.1007/s00601-015-0949-0}, number={6-9}, journal={FEW-BODY SYSTEMS}, author={Salamu, Y. and Ji, C. -R. and Melnitchouk, W. and Wang, P.}, year={2015}, month={Sep}, pages={355–362} }
@article{choi_ji_2015, title={Consistency of the light-front quark model with chiral symmetry in the pseudoscalar meson analysis}, volume={91}, DOI={10.1103/physrevd.91.014018}, abstractNote={We discuss the link between the chiral symmetry of QCD and the numerical results of the light-front quark model (LFQM), analyzing both the two-point and three-point functions of a pseudoscalar meson from the perspective of the vacuum fluctuation consistent with the chiral symmetry of QCD. The two-point and three-point functions are exemplified in this work by the twist-2 and twist-3 distribution amplitudes of a pseudoscalar meson and the pion elastic form factor, respectively. The present analysis of the pseudoscalar meson commensurates with the previous analysis of the vector meson two-point function and fortifies our observation that the LFQM with effective degrees of freedom represented by the constituent quark and antiquark may provide the view of effective zero-mode cloud around the quark and antiquark inside the meson. Consequently, the constituents dressed by the zero-mode cloud may be expected to satisfy the chiral symmetry of QCD. Our results appear consistent with this expectation and effectively indicate that the constituent quark and antiquark in the LFQM may be considered as the dressed constituents including the zero-mode quantum fluctuations from the vacuum.}, number={1}, journal={Physical Review. D, Particles, Fields, Gravitation, and Cosmology}, author={Choi, H. M. and Ji, Chueng-Ryong}, year={2015} }
@article{ji_li_suzuki_2015, title={Electromagnetic gauge field interpolation between the instant form and the front form of the Hamiltonian dynamics}, volume={91}, ISSN={["1550-2368"]}, DOI={10.1103/physrevd.91.065020}, abstractNote={We present the electromagnetic gauge field interpolation between the instant form and the front form of the relativistic Hamiltonian dynamics and extend our interpolation of the scattering amplitude presented in the simple scalar field theory to the case of the electromagnetic gauge field theory with the scalar fermion fields known as the scalar quantum electrodynamics (sQED) theory. We find that the Coulomb gauge in the instant form dynamics and the light-front gauge in the front form dynamics, or the light-front dynamics (LFD), are naturally linked by the unified general physical gauge that interpolates between these two forms of dynamics and derive the spin-1 polarization vector for the photon that can be generally applicable for any interpolation angle. The corresponding photon propagator for an arbitrary interpolation angle is found and examined in terms of the gauge field polarization and the interpolating time ordering. Using these results, we calculate the lowest-order scattering processes for an arbitrary interpolation angle in sQED. We provide an example of breaking the reflection symmetry under the longitudinal boost, ${P}^{z}\ensuremath{\leftrightarrow}\ensuremath{-}{P}^{z}$, for the time-ordered scattering amplitude in any interpolating dynamics except the LFD and clarify the confusion in the prevailing notion of the equivalence between the infinite momentum frame and the LFD. The particular correlation found in our previous analysis of the scattering amplitude in the simple scalar field theory, coined as the J-shaped correlation, between the total momentum of the system and the interpolation angle persists in the present analysis of the sQED scattering amplitude. We discuss the singular behavior of this correlation in conjunction with the zero-mode issue in the LFD.}, number={6}, journal={PHYSICAL REVIEW D}, author={Ji, Chueng-Ryong and Li, Ziyue and Suzuki, Alfredo Takashi}, year={2015}, month={Mar} }
@article{bakker_ji_2015, title={Extraction of Compton Form Factors in Scalar QED}, volume={56}, ISSN={["1432-5411"]}, DOI={10.1007/s00601-014-0943-y}, abstractNote={When deeply virtual Compton scattering is used as a tool to study the structure of hadrons in an exclusive process, one way to analyze this process is to express the amplitudes in terms of generalized parton distributions (GPDs). The definition of the latter quantities requires a special kinematics, that cannot always be realized in experiments. Therefore, one may use the expression of the scattering amplitudes in terms of the invariant Compton form factors (CFFs) as a stepping stone to finding the GPDs. In a simple case we illustrate the influences of making approximations in the extraction of CFFs on the values obtained.}, number={6-9}, journal={FEW-BODY SYSTEMS}, author={Bakker, Bernard L. G. and Ji, Chueng-Ryong}, year={2015}, month={Sep}, pages={275–280} }
@article{li_an_ji_2015, title={Interpolating helicity spinors between the instant form and the light-front form}, volume={92}, ISSN={["1550-2368"]}, DOI={10.1103/physrevd.92.105014}, abstractNote={We discuss the helicity spinors interpolating between the instant form dynamics (IFD) and the front form dynamics, or the light-front dynamics (LFD), and present the interpolating helicity amplitudes as well as their squares for the scattering of two fermions, and the annihilation of fermion and anti-fermion. We parametrize the interpolation between the two dynamics, IFD and LFD, by an interpolation angle and derive not only the generalized helicity spinors in the $(0,J)\oplus(J,0)$ chiral representation that links naturally the two typical IFD vs. LFD helicity spinors but also the generalized Melosh transformation that relates these generalized helicity spinors to the usual Dirac spinors. Analyzing the directions of the particle momentum and spin with the variation of the interpolation angle, we inspect the whole landscape of the generalized helicity intermediating between the usual Jacob-Wick helicity in the IFD and the light-front helicity in the LFD. Our analysis clarifies the characteristic difference of the helicity amplitudes between the IFD and the LFD. In particular, we find that the behavior of the angle between the momentum direction and the spin direction bifurcates at a critical interpolation angle and the IFD and the LFD separately belong to the two different branches bifurcated at this critical interpolation angle. This finding further clarifies any conceivable confusion in the prevailing notion of the equivalence between the infinite momentum frame and the LFD. The existence of the universal J-curve found in our previous works of scalar field theory and the sQED theory is confirmed in the present work of interpolating helicity amplitudes for the fermion scattering and annihilation processes. In conjunction with the bifurcation of branches, the two boundaries appear in the interpolating helicity amplitudes and interestingly the J-curve persists within these two boundaries.}, number={10}, journal={PHYSICAL REVIEW D}, author={Li, Ziyue and An, Murat and Ji, Chueng-Ryong}, year={2015}, month={Nov} }
@article{ji_2015, title={LIGHT-CONE 2014: Theory and Experiment for Hadrons on the Light-Front}, volume={56}, ISSN={["1432-5411"]}, DOI={10.1007/s00601-015-0985-9}, number={6-9}, journal={FEW-BODY SYSTEMS}, author={Ji, Chueng-Ryong}, year={2015}, month={Sep}, pages={241–242} }
@article{choi_ji_2015, title={Self-Consistent Covariant Description of Twist-3 Distribution Amplitude of a Pseudoscalar Meson in the Light-Front Quark Model}, volume={56}, ISSN={["1432-5411"]}, DOI={10.1007/s00601-014-0925-0}, abstractNote={We discuss the light-front zero-mode issue in the light-front quark model prediction of the twist-3 distribution amplitude of a pseudoscalar meson from the perspective of the vacuum fluctuation consistent with the chiral symmetry of QCD.}, number={6-9}, journal={FEW-BODY SYSTEMS}, author={Choi, Ho-Meoyng and Ji, Chueng-Ryong}, year={2015}, month={Sep}, pages={419–424} }
@article{choi_ji_li_ryu_2015, title={Variational analysis of mass spectra and decay constants for ground state pseudoscalar and vector mesons in the light-front quark model}, volume={92}, ISSN={["1089-490X"]}, DOI={10.1103/physrevc.92.055203}, abstractNote={Using the variational principle, we compute mass spectra and decay constants of ground state pseudoscalar and vector mesons in the light-front quark model (LFQM) with the QCD-motivated effective Hamiltonian including the hyperfine interaction. By smearing out the Dirac $\ensuremath{\delta}$ function in the hyperfine interaction, we avoid the issue of negative infinity in applying the variational principle to the computation of meson mass spectra and provide analytic expressions for the meson mass spectra. Our analysis with the smeared hyperfine interaction indicates that the interaction for the heavy meson sector including the bottom and charm quarks gets more point-like. We also consider the flavor mixing effect in our analysis and determine the mixing angles from the mass spectra of $(\ensuremath{\omega},\ensuremath{\phi})$ and $(\ensuremath{\eta},{\ensuremath{\eta}}^{\ensuremath{'}})$. Our variational analysis with the trial wave function including the two lowest order harmonic oscillator basis functions appears to improve the agreement with the data of meson decay constants and the heavy meson mass spectra over the previous computation handling the hyperfine interaction as perturbation.}, number={5}, journal={PHYSICAL REVIEW C}, author={Choi, Ho-Meoyng and Ji, Chueng-Ryong and Li, Ziyue and Ryu, Hui-Young}, year={2015}, month={Nov} }
@article{bakker_ji_2014, title={A Study of Compton Form Factors in Scalar QED}, volume={55}, ISSN={["1432-5411"]}, DOI={10.1007/s00601-014-0820-8}, number={5-7}, journal={FEW-BODY SYSTEMS}, author={Bakker, Bernard L. G. and Ji, Chueng-Ryong}, year={2014}, month={Jun}, pages={395–400} }
@inproceedings{ji_2014, title={Hidden color}, volume={543}, booktitle={1st tensor polarized solid target workshop}, author={Ji, C. R.}, year={2014} }
@inproceedings{ji_bakker_choi_suzuki_2014, title={Ideas of four-fermion operators in electromagnetic form factor calculations}, volume={73}, ISSN={2100-014X}, url={http://dx.doi.org/10.1051/EPJCONF/20147306006}, DOI={10.1051/EPJCONF/20147306006}, abstractNote={Four-fermion operators have been utilized in the past to link the quark-exchange processes in the interaction of hadrons with the effective meson-exchange amplitudes. In this presentation, we apply the similar idea of Fierz rearrangement to the electromagnetic processes and focus on the electromagnetic form factors of nucleon and electron. We explain the motivation of using four-fermion operators and discuss the advantage of this method in computing electromagnetic processes.}, booktitle={EPJ Web of Conferences}, publisher={EDP Sciences}, author={Ji, Chueng-Ryong and Bakker, Bernard L.G. and Choi, Ho-Meoyng and Suzuki, Alfredo T.}, editor={Battaglieri, M. and D'Angelo, A. and De Vita, R. and Pascolini, A. and Salmè, G.Editors}, year={2014}, pages={06006} }
@article{ji_bakker_2014, title={Kinematic Issues of GPDs in DVCS}, volume={251-252}, ISSN={0920-5632}, url={http://dx.doi.org/10.1016/J.NUCLPHYSBPS.2014.04.013}, DOI={10.1016/J.NUCLPHYSBPS.2014.04.013}, abstractNote={Generalized Parton Distributions (GPDs) in Deeply Virtual Compton Scattering (DVCS) have been widely recognized and used as a useful tool to explore the quark and gluon structure of the target hadrons. However, we recently pointed out treacherous kinematic issues in analyzing DVCS in terms of GPDs. We present our key findings in the simplest possible level of complete amplitude including the lepton current. We also discuss an implication on theoretical frameworks to cover the kinematic region of DVCS experiment with the 12 GeV upgrade at Jefferson Lab.}, journal={Nuclear Physics B - Proceedings Supplements}, publisher={Elsevier BV}, author={Ji, Chueng-Ryong and Bakker, Bernard L.G.}, year={2014}, month={Jun}, pages={75–80} }
@inproceedings{ji_bakker_2014, title={Kinematic Issues of GPDs in DVCS}, volume={251}, booktitle={Nuclear Physics. B, Proceedings, Supplements}, author={Ji, C. R. and Bakker, B. L. G.}, year={2014}, pages={75–80} }
@article{choi_ji_2014, title={Light-Front Zero-Mode Issue on the Vector Meson Decay Constant}, volume={55}, ISSN={["1432-5411"]}, DOI={10.1007/s00601-013-0789-8}, abstractNote={We discuss the light-front zero-mode issue in the light-front quark model (LFQM) prediction of a vector meson decay constant from the perspective of the vacuum fluctuation consistent with the chiral symmetry of QCD. We extend the exactly solvable manifestly covariant Bethe–Salpeter model calculation to the more phenomenologically accessible realistic LFQM and present a self-consistent covariant description of the vector meson decay constant analyzing the twist-2 and twist-3 quark-antiquark distribution amplitudes with even chirality.}, number={5-7}, journal={FEW-BODY SYSTEMS}, author={Choi, Ho-Meoyng and Ji, Chueng-Ryong}, year={2014}, month={Jun}, pages={435–440} }
@article{bakker_bassetto_brodsky_broniowski_dalley_frederico_głazek_hiller_ji_karmanov_et al._2014, title={Light-front quantum chromodynamics: A framework for the analysis of hadron physics}, volume={251-252}, ISSN={0920-5632}, url={http://dx.doi.org/10.1016/J.NUCLPHYSBPS.2014.05.004}, DOI={10.1016/J.NUCLPHYSBPS.2014.05.004}, abstractNote={An outstanding goal of physics is to find solutions that describe hadrons in the theory of strong interactions, Quantum Chromodynamics (QCD). For this goal, the light-front Hamiltonian formulation of QCD (LFQCD) is a complementary approach to the well-established lattice gauge method. LFQCD offers access to the hadrons' nonperturbative quark and gluon amplitudes, which are directly testable in experiments at existing and future facilities. We present an overview of the promises and challenges of LFQCD in the context of unsolved issues in QCD that require broadened and accelerated investigation. We identify specific goals of this approach and address its quantifiable uncertainties.}, journal={Nuclear Physics B - Proceedings Supplements}, publisher={Elsevier BV}, author={Bakker, B.L.G. and Bassetto, A. and Brodsky, S.J. and Broniowski, W. and Dalley, S. and Frederico, T. and Głazek, S.D. and Hiller, J.R. and Ji, C.-R. and Karmanov, V. and et al.}, year={2014}, month={Jun}, pages={165–174} }
@misc{bakker_ji_2014, title={Nuclear chromodynamics: Novel nuclear phenomena predicted by QCD}, volume={74}, ISSN={["1873-2224"]}, DOI={10.1016/j.ppnp.2013.10.001}, abstractNote={With the acceptance of QCD as the fundamental theory of strong interactions, one of the basic problems in the analysis of nuclear phenomena became how to consistently account for the effects of the underlying quark/gluon structure of nucleons and nuclei. Besides providing more detailed understanding of conventional nuclear physics, QCD may also point to novel phenomena accessible by new or upgraded nuclear experimental facilities. We review several interesting applications of QCD to nuclear physics.}, journal={PROGRESS IN PARTICLE AND NUCLEAR PHYSICS}, author={Bakker, Bernard L. G. and Ji, Chueng-Ryong}, year={2014}, month={Jan}, pages={1–34} }
@article{ji_bakker_li_suzuki_2014, title={Scattering Amplitudes Interpolating Between Instant Form and Front Form of Relativistic Dynamics}, volume={55}, ISSN={["1432-5411"]}, DOI={10.1007/s00601-013-0796-9}, number={5-7}, journal={FEW-BODY SYSTEMS}, author={Ji, Chueng-Ryong and Bakker, Bernard L. G. and Li, Ziyue and Suzuki, Alfredo T.}, year={2014}, month={Jun}, pages={425–434} }
@article{choi_ji_2014, title={Self-consistent covariant description of vector meson decay constants and chirality-even quark-antiquark distribution amplitudes up to twist 3 in the light-front quark model}, volume={89}, ISSN={["1550-2368"]}, DOI={10.1103/physrevd.89.033011}, abstractNote={Although the meson decay amplitude described by a two-point function may be regarded as one of the simplest possible physical observables, it is interesting that this apparently simple amplitude bears abundant fundamental information on QCD vacuum dynamics and chiral symmetry. The light-front zero-mode issue of the vector meson decay constant ${f}_{V}$ is in this respect highly nontrivial and deserves careful analysis. We discuss the zero-mode issue in the light-front quark model (LFQM) prediction of ${f}_{V}$ from the perspective of the vacuum fluctuation consistent with the chiral symmetry of QCD. We extend the exactly solvable, manifestly covariant Bethe-Salpeter model calculation to the more phenomenologically accessible, realistic light-front quark model and present a self-consistent covariant description of ${f}_{V}$, analyzing the twist-2 and twist-3 quark-antiquark distribution amplitudes with even chirality.}, number={3}, journal={PHYSICAL REVIEW D}, author={Choi, Ho-Meoyng and Ji, Chueng-Ryong}, year={2014}, month={Feb} }
@article{ji_melnitchouk_thomas_2013, title={Anatomy of relativistic pion loop corrections to the electromagnetic nucleon coupling}, volume={88}, ISSN={["1550-2368"]}, DOI={10.1103/physrevd.88.076005}, abstractNote={We present a relativistic formulation of pion loop corrections to the coupling of photons with nucleons on the light-front. Vertex and wave function renormalization constants are computed to lowest order in the pion field, including their nonanalytic behavior in the chiral limit, and studied numerically as a function of the ultraviolet cutoff. Particular care is taken to explicitly verify gauge invariance and Ward-Takahashi identity constraints to all orders in the m_pi expansion. The results are used to compute the chiral corrections to matrix elements of local operators, related to moments of deep-inelastic structure functions. Finally, comparisons of results for pseudovector and pseudoscalar coupling allows the resolution of a long-standing puzzle in the computation of pion cloud corrections to structure function moments.}, number={7}, journal={PHYSICAL REVIEW D}, author={Ji, Chueng-Ryong and Melnitchouk, W. and Thomas, A. W.}, year={2013}, month={Oct} }
@misc{ji_bakker_2013, title={Conceptual issues concerning generalized parton distributions}, volume={22}, number={2}, journal={International Journal of Modern Physics. E, Nuclear Physics}, author={Ji, C. R. and Bakker, B. L. G.}, year={2013} }
@article{ji_melnitchouk_thomas_2013, title={Disorder-assisted melting and the glass transition in amorphous solids comment on "Taming the Pion Cloud of the Nucleon''}, volume={110}, number={17}, journal={Physical Review Letters}, author={Ji, C. R. and Melnitchouk, W. and Thomas, A. W.}, year={2013} }
@article{ji_bakker_choi_suzuki_2013, title={Ideas of four-fermion operators in electromagnetic form factor calculations}, volume={87}, ISSN={["1550-2368"]}, DOI={10.1103/physrevd.87.093004}, abstractNote={Four-fermion operators have been utilized in the past to link the quark-exchange processes in the interaction of hadrons with the effective meson-exchange amplitudes. In this paper, we apply the similar idea of a Fierz rearrangement to the electromagnetic processes and focus on the electromagnetic form factors of the nucleon and the electron. We explain the motivation of using four-fermion operators and discuss the advantage of this method in computing electromagnetic processes.}, number={9}, journal={PHYSICAL REVIEW D}, author={Ji, Chueng-Ryong and Bakker, Bernard L. G. and Choi, Ho-Meoyng and Suzuki, Alfredo T.}, year={2013}, month={May} }
@inproceedings{ji_bakker_choi_suzuki_2013, title={Ideas of four-fermion operators in hadron physics}, volume={6}, number={1}, booktitle={Light cone cracow 2012: modern approaches to nonperturbative gauge theories and their applications}, author={Ji, C. R. and Bakker, B. L. G. and Choi, H. M. and Suzuki, A. T.}, year={2013}, pages={117–123} }
@article{ji_suzuki_2013, title={Interpolating scattering amplitudes between the instant form and the front form of relativistic dynamics}, volume={87}, ISSN={["1550-2368"]}, DOI={10.1103/physrevd.87.065015}, abstractNote={Among the three forms of relativistic Hamiltonian dynamics proposed by Dirac in 1949, the instant form and the front form can be interpolated by introducing an interpolation angle between the ordinary time $t$ and the light-front time $(t+z/c)/\sqrt{2}$. Using this method, we introduce the interpolating scattering amplitude that links the corresponding time-ordered amplitudes between the two forms of dynamics and provide the physical meaning of the kinematic transformations as they allow the invariance of each individual time-ordered amplitude for an arbitrary interpolation angle. In particular, it exhibits that the longitudinal boost is kinematical only in the front form dynamics, or the light-front dynamics (LFD), but not in any other interpolation angle dynamics. It also shows that the disappearance of the connected contributions to the current arising from the vacuum occurs when the interpolation angle is taken to yield the LFD. Since it doesn't require the infinite momentum frame (IMF) to show this disappearance and the proof is independent of reference frames, it resolves the confusion between the LFD and the IMF. The well-known utility of IMF usually discussed in the instant form dynamics is now also extended to any other interpolation angle dynamics using our interpolating scattering amplitudes.}, number={6}, journal={PHYSICAL REVIEW D}, author={Ji, Chueng-Ryong and Suzuki, Alfredo Takashi}, year={2013}, month={Mar} }
@article{ji_bakker_choi_2013, title={Light-Front Dynamics in Hadron Physics}, volume={54}, ISSN={["1432-5411"]}, DOI={10.1007/s00601-012-0330-5}, number={1-4}, journal={FEW-BODY SYSTEMS}, author={Ji, Chueng-Ryong and Bakker, Bernard L. G. and Choi, Ho-Meoyng}, year={2013}, month={Mar}, pages={63–69} }
@article{burkardt_hendricks_ji_melnitchouk_thomas_2013, title={Pion momentum distributions in the nucleon in chiral effective theory}, volume={87}, ISSN={["1550-2368"]}, DOI={10.1103/physrevd.87.056009}, abstractNote={We compute the light-cone momentum distributions of pions in the nucleon in chiral effective theory using both pseudovector and pseudoscalar pion-nucleon couplings. For the pseudovector coupling we identify \delta-function contributions associated with end-point singularities arising from the pion-nucleon rainbow diagrams, as well as from pion bubble and tadpole diagrams which are not present in the pseudoscalar model. Gauge invariance is demonstrated, to all orders in the pion mass, with the inclusion of Kroll-Ruderman couplings involving operator insertions at the \pi NN vertex. The results pave the way for phenomenological applications of pion cloud models that are manifestly consistent with the chiral symmetry properties of QCD.}, number={5}, journal={PHYSICAL REVIEW D}, author={Burkardt, M. and Hendricks, K. S. and Ji, Chueng-Ryong and Melnitchouk, W. and Thomas, A. W.}, year={2013}, month={Mar} }
@article{choi_ji_2013, title={Relativistic Covariance of Light-Front Few-Body Systems in Hadron Physics}, volume={54}, ISSN={["1432-5411"]}, DOI={10.1007/s00601-012-0535-7}, abstractNote={We study the light-front covariance of a vector-meson decay constant using a manifestly covariant fermion field theory model in (3 + 1) dimensions. The light-front zero-mode issues are analyzed in terms of polarization vectors and method of identifying the zero-mode operator and of obtaining the light-front covariant decay constant is discussed.}, number={7-10}, journal={FEW-BODY SYSTEMS}, author={Choi, Ho-Meoyng and Ji, Chueng-Ryong}, year={2013}, month={Aug}, pages={1633–1636} }
@article{bakker_ji_2012, title={Kinematical Issues in the GPD Formulation of DVCS}, volume={52}, ISSN={["1432-5411"]}, DOI={10.1007/s00601-012-0319-0}, abstractNote={The kinematics used in computing deeply virtual Compton scattering makes a significant difference in terms of the widely used reduced operators that define generalized parton distributions. We analyze this difference at tree-level.}, number={3-4}, journal={FEW-BODY SYSTEMS}, author={Bakker, Bernard L. G. and Ji, Chueng-Ryong}, year={2012}, month={May}, pages={285–290} }
@article{choi_ji_2012, title={Light-Front Zero-Mode Issue for the Transition Form Factors Between Pseudoscalar and Vector Mesons}, volume={52}, ISSN={["1432-5411"]}, DOI={10.1007/s00601-011-0294-x}, number={3-4}, journal={FEW-BODY SYSTEMS}, author={Choi, Ho-Meoyng and Ji, Chueng-Ryong}, year={2012}, month={May}, pages={409–414} }
@article{ji_tokunaga_2012, title={Light-front dynamic analysis of bound states in a scalar field model}, volume={86}, ISSN={["1550-2368"]}, DOI={10.1103/physrevd.86.054011}, abstractNote={The light-front dynamic of the scalar field model theory is analyzed to solve the two-body bound-state problem. The light-front two-body bound-state equation is extended to the full light-front dynamic kernel including the ladder, cross-ladder, stretched-box, and particle-antiparticle creation/annihilation effects to study the contributions of higher Fock states. The light-front two-body equation is also modified by the term corresponding to the self-energy corrections and counterterms. Using the variational principle, we obtain the numerical result of the binding energy B versus the coupling constant $\ensuremath{\alpha}$ for various mass ratios of the constituent particles including the cases of nonzero exchange particle mass. We also discuss the correlation between the mass spectrum and the corresponding bound-state wave function.}, number={5}, journal={PHYSICAL REVIEW D}, author={Ji, Chueng-Ryong and Tokunaga, Yukihisa}, year={2012}, month={Sep} }
@article{ji_2012, title={Pion Loops in Chiral Perturbation Theory and Light-Front Dynamics}, volume={52}, ISSN={["0177-7963"]}, DOI={10.1007/s00601-011-0270-5}, number={3-4}, journal={FEW-BODY SYSTEMS}, author={Ji, Chueng-Ryong}, year={2012}, month={May}, pages={421–426} }
@inproceedings{ji_melnitchouk_2011, place={New York}, title={Equivalence of light-front and covariant approaches in meson-baryon interactions}, volume={1374}, url={http://dx.doi.org/10.1063/1.3647214}, DOI={10.1063/1.3647214}, abstractNote={We demonstrate the equivalence of the light‐front, equal‐time and covariant formulations in meson‐baryon interactions. In particular, we discuss the self‐energy Σ of a nucleon dressed by pion loops with the pseudovector πNN coupling. It is shown that the leading nonanalytic behavior of Σ is equivalent whichever formulations are used for the derivation.}, booktitle={AIP Conference Proceedings}, publisher={AIP}, author={Ji, Chueng-Ryong and Melnitchouk, Wally}, year={2011}, pages={609–612} }
@article{bakker_ji_2011, title={Issues in the GPD Formulation of DVCS}, volume={50}, ISSN={["0177-7963"]}, DOI={10.1007/s00601-010-0190-9}, abstractNote={The kinematics used in computing deeply virtual Compton scattering makes a dramatic difference in terms of the widely used reduced operators that define generalized parton distributions. We analyze this difference at tree-level.}, number={1-4}, journal={FEW-BODY SYSTEMS}, author={Bakker, Bernard L. G. and Ji, Chueng-Ryong}, year={2011}, month={May}, pages={363–365} }
@article{choi_ji_2011, title={Light-front dynamic analysis of transition form factors in the process of P -> V(l)v(l)}, volume={856}, ISSN={["0375-9474"]}, DOI={10.1016/j.nuclphysa.2011.03.001}, abstractNote={We investigate the light-front zero-mode contribution to the weak transition form factors between pseudoscalar and vector mesons using a covariant fermion field theory model in $(3+1)$ dimensions. In particular, we discuss the form factors $a_-(q^2)$ and $f(q^2)$ which have been suspected to have the zero-mode contribution in the $q^+=0$ frame. While the zero-mode contribution in principle depends on the form of the vector meson vertex $\Gamma^\mu=\gamma^\mu - (2k-P_V)^\mu/D$, the form factor $f(q^2)$ is found to be free from the zero mode if the denominator $D$ contains the term proportional to the light-front longitudinal momentum fraction factor $(1/x)^n$ of the struck quark with the power $n>0$. Although the form factor $a_-(q^2)$ is not free from the zero mode, the zero-mode contribution comes only either from the simple vertex $\Gamma^\mu=\gamma^\mu$ term or from the other term just with a constant $D$ (i.e. $n=0$), but not with the momentum-dependent denominator (i.e. $D\sim (1/x)^n$ with $n>0$). We identify the zero-mode contribution to $a_-(q^2)$ and incorporate it as a convolution of the zero-mode operator with the initial and final state light-front wave functions. The covariance (i.e. frame independence) of our model has been checked by performing the light-front calculations both in the $q^+=0$ and $q^+\neq 0$ frames. We present our numerical result for the $B\to\rho$ transition for an explicit demonstration of our findings.}, number={1}, journal={NUCLEAR PHYSICS A}, author={Choi, Ho-Meoyng and Ji, Chueng-Ryong}, year={2011}, month={Apr}, pages={95–111} }
@article{choi_ji_2011, title={Light-front zero-mode contribution to the tensor form factors for the exclusive rare P -> Vl(+)l(-) decays}, volume={696}, ISSN={["0370-2693"]}, DOI={10.1016/j.physletb.2011.01.021}, abstractNote={We study the light-front zero-mode contribution to the tensor form factors Ti (i=1,2,3) for the exclusive rare P→Vℓ+ℓ− decays using a covariant fermion field theory model in (3+1) dimensions. While the zero-mode contribution in principle depends on the form of the vector meson vertex Γμ=γμ−(2k−PV)μ/D, the three tensor form factors Ti (i=1,2,3) are found to be free from the zero mode if the denominator D contains the term proportional to the light-front energy or the longitudinal momentum fraction factor (1/x)n of the struck quark with the power n>0. Since the denominator D used in the light-front quark model (LFQM) has the power n=1/2, the three tensor form factors Ti (i=1,2,3) can be computed in LFQM safely without involving any complicate zero-mode contribution. The lack of zero-mode contribution benefits the phenomenology with LFQM.}, number={5}, journal={PHYSICS LETTERS B}, author={Choi, Ho-Meoyng and Ji, Chueng-Ryong}, year={2011}, month={Feb}, pages={518–522} }
@inbook{choi_ji_2011, place={Berlin Heidelberg}, series={Springer Proceedings in Physics}, title={Nonleptonic Two-Body Decays of the B c Mesons in Light-Front Quark Model}, ISBN={9783642179129 9783642179136}, ISSN={0930-8989 1867-4941}, url={http://dx.doi.org/10.1007/978-3-642-17913-6_8}, DOI={10.1007/978-3-642-17913-6_8}, abstractNote={We study exclusive nonleptonic two-body B c → (D (s), η c , B (s)) + F decays with F (pseudoscalar or vector meson) factored out in the QCD factorization approach. The nonleptonic decay amplitudes are related to the product of meson decay constants and the form factors for semileptonic B c decays. As inputs in obtaining the branching ratios for a large set of nonleptonic B c decays, we use the weak form factors for the semileptonic B c → (D (s), η c , B (s)) decays in the whole kinematical region and the unmeasured meson decay constants obtained from our previous light-front quark model.}, booktitle={EKC 2010}, publisher={Springer}, author={Choi, Ho-Meoyng and Ji, Chueng-Ryong}, editor={Han, M.W. and Lee, J.Editors}, year={2011}, pages={59–66}, collection={Springer Proceedings in Physics} }
@article{bakker_ji_2011, title={Spin filter in deeply virtual Compton scattering amplitudes}, volume={83}, ISSN={["1550-2368"]}, DOI={10.1103/physrevd.83.091502}, abstractNote={Whether the kinematics includes the hard transverse photon momenta or not makes a dramatic difference in computing deeply virtual Compton scattering in terms of the widely used reduced operators that define generalized parton distributions. Our tree-level complete deeply virtual Compton scattering amplitude including the lepton current plays the role of spin filter to analyze such kinematic dependence on the contribution of longitudinally polarized virtual photon as well as the conservation of angular momentum.}, number={9}, journal={PHYSICAL REVIEW D}, author={Bakker, Bernard L. G. and Ji, Chueng-Ryong}, year={2011}, month={May} }
@article{ji_bakker_2010, title={GPD Extraction from DVCS in LFD}, volume={199}, ISSN={0920-5632}, url={http://dx.doi.org/10.1016/j.nuclphysbps.2010.02.003}, DOI={10.1016/j.nuclphysbps.2010.02.003}, abstractNote={We discuss the issue of extracting the generalized parton distribution (GPD) from deeply virtual Compton scattering (DVCS). We focus our discussion on the fermion propagator between the two photons in the handbag diagram taking the well-known kinematics frequently used in the light-front dynamics (LFD). We compare the results between the full calculation of the tree level Compton scattering amplitude and the reduced calculation using the GPD formulation. We present the treacherous points in obtaining the agreement between the two results: one from the full calculation of the DVCS and the other from the reduced calculation of the GPD formulation. The utility of our calculation is also discussed.}, number={1}, journal={Nuclear Physics B - Proceedings Supplements}, publisher={Elsevier BV}, author={Ji, Chueng-Ryong and Bakker, Bernard L.G.}, year={2010}, month={Feb}, pages={16–25} }
@article{blasone_capolupo_ji_vitiello_2010, title={ON FLAVOR CONSERVATION IN WEAK INTERACTION DECAYS INVOLVING MIXED NEUTRINOS}, volume={25}, ISSN={["1793-656X"]}, DOI={10.1142/s0217751x10050445}, abstractNote={In the context of quantum field theory (QFT), we compute the amplitudes of weak interaction processes such as $ W^{+} \rightarrow e^{+} + \nu_{e}$ and $ W^{+} \rightarrow e^{+} + \nu_{\mu}$ by using different representations of flavor states for mixed neutrinos. Analyzing the short time limit of the above amplitudes, we find that the neutrino states defined in QFT as eigenstates of the flavor charges lead to results consistent with lepton charge conservation. On the contrary, the Pontecorvo flavor states produce a violation of lepton charge in the vertex, which is in contrast with what expected at tree level in the Standard Model.}, number={22}, journal={INTERNATIONAL JOURNAL OF MODERN PHYSICS A}, author={Blasone, Massimo and Capolupo, Antonio and Ji, Chueng-Ryong and Vitiello, Giuseppe}, year={2010}, month={Sep}, pages={4179–4194} }
@article{choi_ji_2010, title={Semileptonic Bc decays in the light-front quark model}, volume={199}, ISSN={0920-5632}, url={http://dx.doi.org/10.1016/j.nuclphysbps.2010.02.037}, DOI={10.1016/j.nuclphysbps.2010.02.037}, abstractNote={We investigate the exclusive semileptonic Bc→(D,ηc,B,Bs)ℓνℓ, ηb→Bcℓνℓ(ℓ=e,μ,τ) decays using the light-front quark model constrained by the variational principle for the QCD motivated effective Hamiltonian. The form factors f+(q2) and f−(q2) are obtained from the analytic continuation method in the q+=0 frame. While the form factor f+(q2) is free from the zero mode, the form factor f−(q2) is not free from the zero mode in the q+=0 frame. Using our effective method to relate the non-wave function vertex to the light-front valence wave function, we incorporate the zero-mode contribution as a convolution of zero-mode operator with the initial and final state wave functions.}, number={1}, journal={Nuclear Physics B - Proceedings Supplements}, publisher={Elsevier BV}, author={Choi, Ho-Meoyng and Ji, Chueng-Ryong}, year={2010}, month={Feb}, pages={240–245} }
@inproceedings{bakker_ji_2010, title={Some Issues in Deeply-Virtual Compton Scattering}, volume={3}, ISSN={2100-014X}, url={http://dx.doi.org/10.1051/epjconf/20100303030}, DOI={10.1051/epjconf/20100303030}, abstractNote={Compton scattering provides a unique tool for studying hadron structure. In contrast to elastic electron scattering, which provides information about the hadron’s structure in terms of form factors, Compton scattering is more versatile, as the basic process is the coupling of two electro-magnetic currents. Therefore, the hadronic structure can be described at high momentum transfer in the language of generalized parton distributions (GPDs), which code information about the light-front wave functions of the probed hadrons. In this paper we discuss some issues involved in the application of the GPD idea, in particular the eﬀectivity of Compton scattering as a ﬁlter of the hadron structure.}, booktitle={EPJ Web of Conferences}, publisher={EDP Sciences}, author={Bakker, B.L.G. and Ji, C.-R.}, year={2010}, pages={03030} }
@article{bakker_ji_2010, title={Treacherous Points in Deeply Virtual Compton Scattering}, volume={199}, ISSN={0920-5632}, url={http://dx.doi.org/10.1016/j.nuclphysbps.2010.02.034}, DOI={10.1016/j.nuclphysbps.2010.02.034}, abstractNote={Deeply virtual Compton scattering is proposed as a way to probe hadronic matter beyond generalized parton distributions. In this paper, it is argued that depending on the kinematics used, some singularities may occur that render the connection between the experimental data and the generalized parton distributions problematic.}, number={1}, journal={Nuclear Physics B - Proceedings Supplements}, publisher={Elsevier BV}, author={Bakker, Bernard L.G. and Ji, Chueng-Ryong}, year={2010}, month={Feb}, pages={225–230} }
@article{ji_melnitchouk_thomas_2009, title={Equivalence of pion loops in equal-time and light-front dynamics}, volume={80}, ISSN={["1550-2368"]}, DOI={10.1103/physrevd.80.054018}, abstractNote={We demonstrate the equivalence of the light-front and equal-time formulations of pionic corrections to nucleon properties. As a specific example, we consider the self-energy $\ensuremath{\Sigma}$ of a nucleon dressed by pion loops, for both pseudovector and pseudoscalar $\ensuremath{\pi}NN$ couplings. We derive the leading and next-to-leading nonanalytic behavior of $\ensuremath{\Sigma}$ on the light front, and show explicitly their equivalence in the rest frame and infinite momentum frame in equal-time quantization, as well as in a manifestly covariant formulation.}, number={5}, journal={PHYSICAL REVIEW D}, author={Ji, Chueng-Ryong and Melnitchouk, W. and Thomas, A. W.}, year={2009}, month={Sep} }
@article{choi_ji_2009, title={Nonleptonic two-body decays of the B-c meson in the light-front quark model and the QCD factorization approach}, volume={80}, ISSN={["1550-2368"]}, DOI={10.1103/physrevd.80.114003}, abstractNote={We study exclusive nonleptonic two-body ${B}_{c}\ensuremath{\rightarrow}({D}_{(s)},{\ensuremath{\eta}}_{c},{B}_{(s)})+F$ decays with $F$ (pseudoscalar or vector mesons) factored out in the QCD factorization approach. The nonleptonic decay amplitudes are related to the product of meson decay constants and the form factors for semileptonic ${B}_{c}$ decays. As inputs in obtaining the branching ratios for a large set of nonleptonic ${B}_{c}$ decays, we use the weak form factors for the semileptonic ${B}_{c}\ensuremath{\rightarrow}({D}_{(s)},{\ensuremath{\eta}}_{c},{B}_{(s)})$ decays in the whole kinematical region and the unmeasured meson decay constants obtained from our previous light-front quark model. We compare our results for the branching ratios with those of other theoretical studies.}, number={11}, journal={PHYSICAL REVIEW D}, author={Choi, Ho-Meoyng and Ji, Chueng-Ryong}, year={2009}, month={Dec} }
@article{blasone_capolupo_ji_vitiello_2009, title={On flavor violation for massive and mixed neutrinos}, volume={188}, ISSN={0920-5632}, url={http://dx.doi.org/10.1016/j.nuclphysbps.2009.02.007}, DOI={10.1016/j.nuclphysbps.2009.02.007}, abstractNote={We discuss flavor charges and states for interacting mixed neutrinos in QFT. We show that the Pontecorvo states are not eigenstates of the flavor charges. This implies that their use in describing the flavor neutrinos produces a violation of lepton charge conservation in the production/detection vertices. The flavor states defined as eigenstates of the flavor charges give the correct representation of mixed neutrinos in charged current weak interaction processes.}, journal={Nuclear Physics B - Proceedings Supplements}, publisher={Elsevier BV}, author={Blasone, M. and Capolupo, A. and Ji, C.R. and Vitiello, G.}, year={2009}, month={Mar}, pages={37–39} }
@article{choi_ji_2009, title={Semileptonic and radiative decays of the Bc meson in the light-front quark model}, volume={80}, ISSN={["1550-2368"]}, DOI={10.1103/physrevd.80.054016}, abstractNote={We investigate the exclusive semileptonic ${B}_{c}\ensuremath{\rightarrow}(D,{\ensuremath{\eta}}_{c},B,{B}_{s})\ensuremath{\ell}{\ensuremath{\nu}}_{\ensuremath{\ell}}$, ${\ensuremath{\eta}}_{b}\ensuremath{\rightarrow}{B}_{c}\ensuremath{\ell}{\ensuremath{\nu}}_{\ensuremath{\ell}}$ ($\ensuremath{\ell}=e,\ensuremath{\mu},\ensuremath{\tau}$) decays using the light-front quark model constrained by the variational principle for the QCD-motivated effective Hamiltonian. The form factors ${f}_{+}({q}^{2})$ and ${f}_{\ensuremath{-}}({q}^{2})$ are obtained from the analytic continuation method in the ${q}^{+}=0$ frame. While the form factor ${f}_{+}({q}^{2})$ is free from the zero mode, the form factor ${f}_{\ensuremath{-}}({q}^{2})$ is not free from the zero mode in the ${q}^{+}=0$ frame. We quantify the zero-mode contributions to ${f}_{\ensuremath{-}}({q}^{2})$ for various semileptonic ${B}_{c}$ decays. Using our effective method to relate the non-wave-function vertex to the light-front valence wave function, we incorporate the zero-mode contribution as a convolution of the zero-mode operator with the initial and final state wave functions. Our results are then compared to the available experimental data and the results from other theoretical approaches. Since the prediction on the magnetic dipole ${B}_{c}^{*}\ensuremath{\rightarrow}{B}_{c}+\ensuremath{\gamma}$ decay turns out to be very sensitive to the mass difference between ${B}_{c}^{*}$ and ${B}_{c}$ mesons, the decay width $\ensuremath{\Gamma}({B}_{c}^{*}\ensuremath{\rightarrow}{B}_{c}\ensuremath{\gamma})$ may help in determining the mass of ${B}_{c}^{*}$ experimentally. Furthermore, we compare the results from the harmonic oscillator potential and the linear potential and identify the decay processes that are sensitive to the choice of confining potential. From the future experimental data on these sensitive processes, one may obtain more realistic information on the potential between the quark and antiquark in the heavy meson system.}, number={5}, journal={PHYSICAL REVIEW D}, author={Choi, Ho-Meoyng and Ji, Chueng-Ryong}, year={2009}, month={Sep} }
@article{choi_ji_2008, title={Conformal symmetry and pion form factor: Space- and timelike region}, volume={77}, ISSN={["1550-2368"]}, DOI={10.1103/physrevd.77.113004}, abstractNote={We extend a recent analysis of the pion electromagnetic form factor constrained by the conformal symmetry to explore the timelike region. We show explicitly that the timelike form factor obtained by the analytic continuation of the spacelike form factor correctly satisfies the dispersion relation. Our results indicate that the quark spin and dynamical mass effects are crucial to yield the realistic features of the vector meson dominance phenomena.}, number={11}, journal={PHYSICAL REVIEW D}, author={Choi, Ho-Meoyng and Ji, Chueng-Ryong}, year={2008}, month={Jun} }
@article{ji_2008, title={Recent Progress in Application of Light-Front Dynamics to Hadron Physics}, volume={53}, ISSN={["0374-4884"]}, DOI={10.3938/jkps.53.3714}, number={6}, journal={JOURNAL OF THE KOREAN PHYSICAL SOCIETY}, author={Ji, Chueng Ryong}, year={2008}, month={Dec}, pages={3714–3718} }
@article{bakker_boomsma_ji_2007, title={Box diagram in Yukawa theory}, volume={75}, ISSN={["1550-2368"]}, DOI={10.1103/physrevd.75.065010}, abstractNote={We present a light-front calculation of the box diagram in Yukawa theory. The covariant box diagram is finite for the case of spin-$1/2$ constituents exchanging spin-0 particles. In light-front dynamics, however, individual time-ordered diagrams are divergent. We analyze the corresponding light-front singularities and show the equivalence between the light-front and covariant results by taming the singularities.}, number={6}, journal={PHYSICAL REVIEW D}, author={Bakker, Bernard L. G. and Boomsma, Jorn K. and Ji, Chueng-Ryong}, year={2007}, month={Mar} }
@article{choi_ji_2007, title={Distribution amplitudes and decay constants for (pi,K,rho,K-*) mesons in the light-front quark model}, volume={75}, ISSN={["1550-2368"]}, DOI={10.1103/physrevd.75.034019}, abstractNote={We present a calculation of the quark distribution amplitudes (DAs), the Gegenbauer moments, and decay constants for $\ensuremath{\pi}$, $\ensuremath{\rho}$, $K$, and ${K}^{*}$ mesons using the light-front quark model. While the quark DA for $\ensuremath{\pi}$ is somewhat broader than the asymptotic one, that for $\ensuremath{\rho}$ meson is very close to the asymptotic one. The quark DAs for $K$ and ${K}^{*}$ show asymmetric form due to the flavor SU(3)-symmetry breaking effect. The decay constants for the transversely polarized $\ensuremath{\rho}$ and ${K}^{*}$ mesons (${f}_{\ensuremath{\rho}}^{T}$ and ${f}_{{K}^{*}}^{T}$) as well as the longitudinally polarized ones (${f}_{\ensuremath{\rho}}$ and ${f}_{{K}^{*}}$) are also obtained. Our averaged values for ${f}_{V}^{T}/{f}_{V}$, i.e. $({f}_{\ensuremath{\rho}}^{T}/{f}_{\ensuremath{\rho}}{)}_{\mathrm{av}}=0.78$ and $({f}_{{K}^{*}}^{T}/{f}_{{K}^{*}}{)}_{\mathrm{av}}=0.84$, are found to be consistent with other model predictions. Especially, our results for the decay constants are in good agreement with the SU(6) symmetry relation, ${f}_{\ensuremath{\rho}({K}^{*})}^{T}=({f}_{\ensuremath{\pi}(K)}+{f}_{\ensuremath{\rho}({K}^{*})})/2$.}, number={3}, journal={PHYSICAL REVIEW D}, author={Choi, Ho-Meoyng and Ji, Chueng-Ryong}, year={2007}, month={Feb} }
@article{ji_bakker_choi_2007, title={New developments in treacherous points of light-front dynamics}, volume={790}, ISSN={["0375-9474"]}, DOI={10.1016/j.nuclphysa.2007.03.099}, abstractNote={Light-front dynamics(LFD) plays an important role in hadron phenomenology. The last few years, however, it has been emphasized that treacherous points such as zero-mode contributions should be taken into account for successful LFD applications to hadron phenomenology. We discuss some examples of treacherous points and present new progress made the last few years to handle them correctly.}, journal={NUCLEAR PHYSICS A}, author={Ji, Chueng-Ryong and Bakker, Bernard L. G. and Choi, Ho-Meoyng}, year={2007}, month={Jun}, pages={583C–587C} }
@book{ji_2007, title={Pedestrian approach to particle physics -- (APCTP monograph)}, ISBN={8995882204}, publisher={Seoul, Korea: Asia Pacific Center for Theoretical Physics}, author={Ji, C.-R.}, year={2007} }
@article{choi_ji_2007, title={Perturbative QCD analysis of exclusive J/psi+eta(c) production in e(+)e(-) annihilation}, volume={76}, ISSN={["1550-2368"]}, DOI={10.1103/physrevd.76.094010}, abstractNote={We analyze the exclusive charmonium $J/\ensuremath{\psi}+{\ensuremath{\eta}}_{c}$ pair production in ${e}^{+}{e}^{\ensuremath{-}}$ annihilation using the nonfactorized perturbative QCD and the light-front quark model (LFQM) that goes beyond the peaking approximation. We effectively include all orders of higher twist terms in the leading order of QCD coupling constant and compare our nonfactorized analysis with the usual factorized analysis in the calculation of the cross section. We also calculate the quark distribution amplitudes, the Gegenbauer moments, and the decay constants for $J/\ensuremath{\psi}$ and ${\ensuremath{\eta}}_{c}$ mesons using our LFQM. Our nonfactorized result enhances the nonrelativistic QCD result by a factor of $3\ensuremath{\sim}4$ at $\sqrt{s}=10.6\text{ }\text{ }\mathrm{GeV}$.}, number={9}, journal={PHYSICAL REVIEW D}, author={Choi, Ho-Meoyng and Ji, Chueng-Ryong}, year={2007}, month={Nov} }
@article{bakker_boomsma_ji_2007, title={Singularities in the light-front Yukawa model}, volume={790}, ISSN={["1873-1554"]}, DOI={10.1016/j.nuclphysa.2007.03.097}, abstractNote={The Yukawa model is discussed in Light-Front Dynamics. Different types of singularities that may occur are mentioned. Two cases are treated in detail: The fermion self energy and the box diagram.}, journal={NUCLEAR PHYSICS A}, author={Bakker, Bernard L. G. and Boomsma, Jorn K. and Ji, Cheung-Ryong}, year={2007}, month={Jun}, pages={573C–577C} }
@article{yu_wang_ji_ma_2007, title={Zero-mode contribution in nucleon-delta transition}, volume={76}, ISSN={["1550-7998"]}, DOI={10.1103/physrevd.76.074009}, abstractNote={We investigate the transition form factors between nucleon and $\ensuremath{\Delta}(1232)$ particles by using a covariant quark-spectator-diquark field theory model in $(3+1)$ dimensions. Performing a light-front calculation in parallel with the manifestly covariant calculation in the light-front helicity basis, we examine the light-front zero-mode contribution to the helicity components of light-front good (``$+$'') current matrix elements. Choosing the light-front gauge (${ϵ}_{h=\ifmmode\pm\else\textpm\fi{}}^{+}=0$) with circular polarization in the Drell-Yan-West frame, we find that only the helicity components $(\frac{1}{2},\frac{1}{2})$ and $(\frac{1}{2},\ensuremath{-}\frac{1}{2})$ of the good current receive the zero-mode contribution. Taking into account the zero mode, we find the prescription independence in obtaining the light-front solution of form factors from any three helicity matrix elements with smeared light-front wave functions. The angular condition, which guarantees the full covariance of different schemes, is recovered.}, number={7}, journal={PHYSICAL REVIEW D}, author={Yu, Jianghao and Wang, Teng and Ji, Chueng-Ryong and Ma, Bo-Qiang}, year={2007}, month={Oct} }
@article{ji_kim_min_vinnikov_2006, title={Canonical transformation and duality in 1+1 dimensional phi(4) and phi(6) theory}, volume={49}, number={6}, journal={Journal of the Korean Physical Society}, author={Ji, C. R. and Kim, J. I. and Min, D. P. and Vinnikov, A. V.}, year={2006}, pages={2253–2270} }
@article{choi_ji_2006, title={Conformal symmetry and pion form factor: Soft and hard contributions}, volume={74}, ISSN={["1550-2368"]}, DOI={10.1103/physrevd.74.093010}, abstractNote={We discuss a constraint of conformal symmetry in the analysis of the pion form factor. The usual power-law behavior of the form factor obtained in the perturbative QCD analysis can also be attained by taking negligible quark masses in the nonperturbative quark model analysis, confirming the recent AdS/CFT correspondence. We analyze the transition from soft to hard contributions in the pion form factor considering a momentum-dependent dynamical quark mass from an appreciable constituent quark mass at low momentum region to a negligible current quark mass at high momentum region. We find a correlation between the shape of nonperturbative quark distribution amplitude and the amount of soft and hard contributions to the pion form factor.}, number={9}, journal={PHYSICAL REVIEW D}, author={Choi, Ho-Meoyng and Ji, Chueng-Ryong}, year={2006}, month={Nov} }
@article{ji_mishchenko_radyushkin_2006, title={Higher Fock-state contributions to the generalized parton distribution of pion}, volume={73}, ISSN={["1550-2368"]}, DOI={10.1103/physrevd.73.114013}, abstractNote={We discuss the higher Fock-state ($q\overline{q}g$) contributions to the nonzero value of the pion generalized parton distribution (GPD) at the crossover point $x=\ensuremath{\zeta}$ between the DGLAP and ERBL regions. Using the phenomenological light-front constituent quark model, we confirm that the higher Fock-state contributions indeed give a nonzero value of the GPD at the crossover point. Iterating the light-front quark model wave function of the lowest $q\overline{q}$ Fock state with the Bethe-Salpeter kernel corresponding to the one-gluon exchange, we include all possible time-ordered $q\overline{q}g$ Fock-state contributions and obtain the pion GPD satisfying necessary sum rules and continuity conditions.}, number={11}, journal={PHYSICAL REVIEW D}, author={Ji, Chueng-Ryong and Mishchenko, Yuriy and Radyushkin, Anatoly}, year={2006}, month={Jun} }
@article{ji_kang_lee_2006, title={Instanton-inspired model of QCD phase transitions and bubble dynamics}, volume={73}, ISSN={["1550-2368"]}, DOI={10.1103/physrevd.73.085003}, abstractNote={We have reinvestigated the collision of gluonic bubbles in an SU(2) model of QCD which was studied by Johnson, Choi, and Kisslinger in the context of the instanton-inspired model of QCD phase transition bubbles with plane-wave approximation. We discuss treacherous points of the instanton-inspired model that cause the violation of causality due to the presence of imaginary gluon fields. By constructing a new slightly modified Lorentzian model where we have three independent real gluon fields, we reanalyzed the process of bubble collisions. Our numerical results show some indication of forming a bubble wall in the colliding region.}, number={8}, journal={PHYSICAL REVIEW D}, author={Ji, CR and Kang, G and Lee, J}, year={2006}, month={Apr} }
@article{bakker_ji_2006, title={Light-front singularities in the Yukawa model}, volume={161}, ISSN={["0920-5632"]}, DOI={10.1016/j.nuclphysbps.2006.08.004}, abstractNote={In light-front dynamics singularites may appear in time-ordered amplitudes that are absent in the manifestly covariant treatment of a system described by the same Lagrangian. Examples are discussed for the case of the Yukawa model. It is shown that both instantaneous contributions to the fermion propagator and higher Fock components are needed to resolve the discrepancy between the two approaches.}, journal={NUCLEAR PHYSICS B-PROCEEDINGS SUPPLEMENTS}, author={Bakker, B. L. G. and Ji, C. -R.}, year={2006}, month={Nov}, pages={15–20} }
@article{hong_ji_min_2006, title={Light-front wavefunction dependence of quark recombination}, volume={73}, ISSN={["1089-490X"]}, DOI={10.1103/physrevc.73.054901}, abstractNote={We present an extension of the recombination formalism to analyze the effects from the variation of the hadron wavefunctions. The hadron spectra are sensitive to the shape of the wavefunctions. However, when we fit the wavefunction parameters to the physical observables, such as the average charge radius, the final spectra are very similar each other. We discuss our numerical results in comparison with the published PHENIX and STAR data at RHIC. In the hadron spectra, the recombination of thermal partons dominates at intermediate transverse momentum ($P_{T}$ = 2 $\sim$ 5 GeV), and the fragmentation dominates at high $P_{T}$ ($>$ 5 GeV). The yield ratios and the nuclear modification factors for various hadron species are also estimated and compared to the experimental data. We present a new prediction on $\bar{p}/p$ and $K^{-}/K^{+}$ ratios, including the jet quenching effects to the fragmentation mechanism.}, number={5}, journal={PHYSICAL REVIEW C}, author={Hong, Byungsik and Ji, Chueng-Ryong and Min, Dong-Pil}, year={2006}, month={May} }
@article{choi_ji_2006, title={Perturbative QCD analysis of exclusive e(+)e(-)-> D[s]+D[s]- cross section at root s=10.6 GeV}, volume={73}, ISSN={["1550-2368"]}, DOI={10.1103/physrevd.73.114020}, abstractNote={We analyze the exclusive pseudoscalar ${D}_{[s]}^{+}{D}_{[s]}^{\ensuremath{-}}$ pair production in ${e}^{+}{e}^{\ensuremath{-}}$ annihilations at $\sqrt{s}=10.6\text{ }\text{ }\mathrm{GeV}$ using a nonfactorized PQCD with the light-front wave function that goes beyond the peaking approximation. We compare our nonfactorized analysis with the usual factorized analysis based on the peaking approximation in the calculation of the cross section for the heavy meson pair production. We also discuss the higher helicity contribution to the cross section. Our analysis provides a constraint on the size of quark transverse momentum inside the $D$ meson from the recent Belle data, ${\ensuremath{\sigma}}_{\mathrm{exp}}({e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{D}^{+}{D}^{\ensuremath{-}})<0.04\text{ }\text{ }[\mathrm{pb}]$.}, number={11}, journal={PHYSICAL REVIEW D}, author={Choi, Ho-Meoyng and Ji, Chueng-Ryong}, year={2006}, month={Jun} }
@article{yu_choi_ji_2006, title={Possibility of determining the parity of the pentaquark Θ+from photoproduction near threshold}, volume={32}, ISSN={0954-3899 1361-6471}, url={http://dx.doi.org/10.1088/0954-3899/32/3/012}, DOI={10.1088/0954-3899/32/3/012}, abstractNote={We discuss the possibility of determining the parity of the $\Theta^+$ baryon from photoproduction $\gamma N\to K\Theta^+$ process near threshold. We utilize the conservation laws of parity and angular momentum for the analysis of angular distributions and spin observables near threshold. Since the discussion is in essence a partial wave analysis of the production mechanism the result should be less dependent on the model parameters. Our analysis shows that the angular distribution and photon polarization asymmetry for the process of neutron target are sensitive to the parity of the $\Theta^+$, but not for the case of proton target. In the case of proton target, the polarization asymmetries of target and recoiled $\Theta^+$ are preferred for parity determination.}, number={3}, journal={Journal of Physics G: Nuclear and Particle Physics}, publisher={IOP Publishing}, author={Yu, Byung Geel and Choi, Tae Keun and Ji, Chueng-Ryong}, year={2006}, month={Feb}, pages={387–405} }
@article{thomson_pang_ji_2006, title={Real and virtual nucleon Compton scattering in the perturbative limit}, volume={73}, ISSN={["1550-2368"]}, DOI={10.1103/physrevd.73.054023}, abstractNote={We present the results of calculations analyzing nucleon Compton scattering to lowest order using perturbative QCD (pQCD) methods. Two scenarios are considered: (1) the incoming photon is real; and (2) the incoming photon is virtual. The case of a real photon has been previously analyzed at least 5 times using pQCD, but no two results are in agreement. Here it is shown that our result agrees with that of Brooks and Dixon published in 2000. The case of a virtual photon has been previously analyzed only once using pQCD. However, doubt has been cast on the validity of that result. The results presented here for the virtual photon are believed to be more reliable. Some consideration is given of how to compare these results with experiment. Following the lead of Brooks and Dixon, for the proton, this involves normalizing the cross section using the Dirac proton form factor, which we also calculate. Finally, there is a comparison of our results with recent experiments.}, number={5}, journal={PHYSICAL REVIEW D}, author={Thomson, R and Pang, A and Ji, CR}, year={2006}, month={Mar} }
@article{ji_bakker_choi_2006, title={Revealing treacherous points for successful light-front phenomenological applications}, volume={161}, ISSN={["0920-5632"]}, DOI={10.1016/j.nuclphysbps.2006.08.011}, abstractNote={Light-front dynamics(LFD) plays an important role in hadron phenomenology as evidenced from recent development of generalized parton distributions and other quantities involving hadrons. For successful LFD applications to hadron phenomenology, however, treacherous points such as zero-mode contributions should be taken into account. For a concrete example of zero-mode contribution, we present Standard Model analysis of vector anomaly in the CP-even form factors of W^{\pm} gauge bosons. Main distinguished features of LFD is discussed in comparison with other Hamiltonian dynamics. We also present a power counting method to correctly pin down which hadron form factors receive the zero-mode contribution and which ones do not. Indications from our analysis to hadron phenomenology are discussed.}, journal={NUCLEAR PHYSICS B-PROCEEDINGS SUPPLEMENTS}, author={Ji, Chueng-Ryong and Bakker, Bernard L. G. and Choi, Ho-Meoyng}, year={2006}, month={Nov}, pages={102–108} }
@article{mishchenko_ji_2005, title={A novel variational approach for quantum field theory: Example of study of the ground state and phase transition in nonlinear sigma model}, volume={20}, ISSN={["0217-751X"]}, DOI={10.1142/S0217751X05026819}, abstractNote={We discuss a novel form of the variational approach in Quantum Field Theory in which the trial quantum configuration is represented directly in terms of relevant expectation values rather than, e.g., increasingly complicated structure from Fock space. The quantum algebra imposes constraints on such expectation values so that the variational problem is formulated here as an optimization under constraints. As an example of application of such approach we consider the study of ground state and critical properties in a variant of nonlinear sigma model.}, number={15}, journal={INTERNATIONAL JOURNAL OF MODERN PHYSICS A}, author={Mishchenko, Y and Ji, CR}, year={2005}, month={Jun}, pages={3488–3494} }
@article{mishchenko_ji_2005, title={Exploring properties of dark and visible mass distribution on different scales in the universe}, volume={20}, ISSN={["0217-751X"]}, DOI={10.1142/S0217751X05025929}, abstractNote={In this short note we discuss recent observation of linear correlation on log-log scale between distribution of dark and visible mass in gravitationally bound systems. The coefficient of such correlation appears to be essentially the same for various systems of dramatically different scales such as spiral galaxies of different luminosities and galaxy clusters. We briefly touch possible interpretations of this observation and implications for the mass of dark matter particle.}, number={14}, journal={INTERNATIONAL JOURNAL OF MODERN PHYSICS A}, author={Mishchenko, Y and Ji, CR}, year={2005}, month={Jun}, pages={3124–3127} }
@article{choi_ji_2005, title={Light-front quark-model analysis of the rho-meson electromagnetic form factors}, volume={36}, ISSN={["0177-7963"]}, DOI={10.1007/s00601-004-0079-6}, number={1-4}, journal={FEW-BODY SYSTEMS}, author={Choi, HM and Ji, CR}, year={2005}, month={Jun}, pages={61–67} }
@article{choi_ji_2005, title={Light-front zero-mode contribution to the good current in weak transitions}, volume={72}, ISSN={["1550-2368"]}, DOI={10.1103/physrevd.72.013004}, abstractNote={We examine the light-front zero-mode contribution to the good(+) current matrix elements between pseudoscalar and vector mesons. In particular, we discuss the transition form factor $f(q^2)$ which has been suspected to have the light-front zero-mode contribution. While the zero-mode contribution in principle depends on the form of the vector meson vertex $\Gamma^\mu=\gamma^\mu - (P_V -2k)^\mu/D$, the form factor $f(q^2)$ is found to be free from the zero-mode contribution if the denominator $D$ contains the term proportional to the light-front energy $(k^-)^{n}$ with the power $n>0$. The lack of zero-mode contribution benefits the light-front quark model phenomenology. We present our numerical calculations for the $B\to\rho$ transition.}, number={1}, journal={PHYSICAL REVIEW D}, author={Choi, HM and Ji, CR}, year={2005}, month={Jul} }
@article{bakker_ji_2005, title={Manifestations of the vector anomaly in covariant and light-front calculations of the anomalous magnetic moment of W-+/- bosons}, volume={71}, ISSN={["1550-2368"]}, DOI={10.1103/physrevd.71.053005}, abstractNote={In the calculation of the anomalous magnetic moment of ${W}^{\ifmmode\pm\else\textpm\fi{}}$ bosons, we discuss vector anomalies occurring in the fermion loop that spoil the predictive power of the theory. While the previous analyses were limited to using essentially the manifestly covariant dimensional regulation method, we extend the analysis using both the manifestly covariant formulation and the light-front Hamiltonian formulation with several different regularization methods. We find that the zero-mode contribution to the helicity zero-to-zero amplitude for the ${W}^{\ifmmode\pm\else\textpm\fi{}}$ gauge bosons is crucial for the correct light-front (LF) calculations. Further, we confirm that the anomaly-free condition found in the analysis of the axial anomaly can also get rid of the vector anomaly in light-front dynamics (LFD) as well as in the manifestly covariant calculations. Our findings in this work may provide a bottom-up fitness test not only to the LF calculations but also to the theory itself, whether it is any extension of the Standard Model or an effective field theoretic model for composite systems.}, number={5}, journal={PHYSICAL REVIEW D}, author={Bakker, BLG and Ji, CR}, year={2005}, month={Mar} }
@article{thomson_ji_2005, title={Nucleon Compton scattering in the perturbative limit}, volume={36}, ISSN={["0177-7963"]}, DOI={10.1007/s00601-004-0107-6}, number={1-4}, journal={FEW-BODY SYSTEMS}, author={Thomson, R and Ji, CR}, year={2005}, month={Jun}, pages={237–240} }
@article{bakker_dewitt_ji_mishchenko_2005, title={Restoring the equivalence between the light-front and manifestly covariant formalisms}, volume={72}, ISSN={["1550-2368"]}, DOI={10.1103/physrevd.72.076005}, abstractNote={We discuss a treacherous point in light-front dynamics (LFD) which should be taken into account to restore complete equivalence with the manifestly covariant formalism. We present examples that require an inclusion of the arc contribution in the light-front energy contour integration in order to achieve the equivalence between the LFD result and the manifestly covariant result.}, number={7}, journal={PHYSICAL REVIEW D}, author={Bakker, BLG and DeWitt, MA and Ji, CR and Mishchenko, Y}, year={2005}, month={Oct} }
@article{dewitt_choi_ji_2005, title={Scalar mesons in the light-front quark model}, volume={36}, ISSN={["1432-5411"]}, DOI={10.1007/s00601-004-0082-y}, number={1-4}, journal={FEW-BODY SYSTEMS}, author={DeWitt, MA and Choi, HM and Ji, CR}, year={2005}, month={Jun}, pages={83–86} }
@article{ji_mishchenko_2005, title={Time-to-space conversion in quantum field theory of flavor mixing}, volume={315}, ISSN={["1096-035X"]}, DOI={10.1016/j.aop.2004.09.004}, abstractNote={We consider the problem of time-to-space conversion in quantum field theory of flavor mixing using a generalization of the wave-packet method in quantum mechanics. We work entirely within the canonical formalism of creation and annihilation operators that allows us, unlike the usual wave-packet formulation, to include the nontrivial effect due to flavor condensation in the vacuum.}, number={2}, journal={ANNALS OF PHYSICS}, author={Ji, CR and Mishchenko, Y}, year={2005}, month={Feb}, pages={488–504} }
@article{ji_bakker_2005, title={Vector anomaly and practicality of light-front dynamics}, volume={36}, ISSN={["0177-7963"]}, DOI={10.1007/s00601-004-0091-x}, number={1-4}, journal={FEW-BODY SYSTEMS}, author={Ji, CR and Bakker, BLG}, year={2005}, month={Jun}, pages={137–144} }
@article{choi_ji_2004, title={Electromagnetic structure of the rho meson in the light-front quark model}, volume={70}, ISSN={["1550-2368"]}, DOI={10.1103/physrevd.70.053015}, abstractNote={We investigate the elastic form factors of the $\ensuremath{\rho}$ mesonin the light-front quark model (LFQM). With the phenomenologically accessiblemeson vertices including the one obtained by the Melosh transformation frequentlyused in the LFQM, we find that only the helicity $0\ensuremath{\rightarrow}0$ matrix element of the plus current receives the zero-modecontribution. We quantify the zero-mode contribution in the helicity $0\ensuremath{\rightarrow}0$ amplitude using the angular condition of spin-1 system.After taking care of the zero-mode issue, we obtain the magnetic ($\ensuremath{\mu}$)and quadrupole ($Q$) momentsof the $\ensuremath{\rho}$ mesonas $\ensuremath{\mu}=1.92$ and $Q=0.43$, respectively, in the LFQM consistent with the Meloshtransformation and compare our results with other available theoretical predictions.}, number={5}, journal={PHYSICAL REVIEW D}, author={Choi, HM and Ji, CR}, year={2004}, month={Sep} }
@article{yu_choi_ji_2004, title={Investigating the parity of the exotic Theta(+) baryon from kaon photoproduction}, volume={70}, ISSN={["1089-490X"]}, DOI={10.1103/physrevc.70.045205}, abstractNote={Based on the hadronic model with the gauge prescription suggested by Ohta and Haberzettl, we investigate the possibility of determining the parity state of the $\Theta^+$ baryon using photon induced processes, $\gamma n\to K^- \Theta^+$ and $\gamma p\to \bar{K}^0 \Theta^+$. The total and differential cross sections are simulated in two versions of pseudovector(PV) and pseudoscalar(PS) coupling schemes and the results are reported both on the positive and negative parity states of the $\Theta^+$ baryon. It is found that in both coupling schemes the total cross sections from the neutron target are in general larger than those from the proton target, regardless of the $\Theta^+$ parities. The cross sections of the $\Theta^+$ production however depend largely on the value of the $\Theta^+$ decay width which is not yet well established. Moreover, there is a wide theoretical uncertainty associated with the different assumption on the gauge prescription in model calculations. We discuss these points by comparing theoretical predictions with the existing experimental data. Our analysis suggests that the observation of the angular distribution rather than just the total cross section in the photoproduction process may be a useful tool to distinguish the parity of the $\Theta^+$ baryon.}, number={4}, journal={PHYSICAL REVIEW C}, author={Yu, BG and Choi, TK and Ji, CR}, year={2004}, month={Oct} }
@article{ji_2004, title={Perspectives of light-front dynamics in few-body systems}, volume={737}, ISSN={["0375-9474"]}, DOI={10.1016/j.nuclphysa.2004.03.086}, abstractNote={The light-front dynamics (LFD) plays an important role in the analyses of few-body systems as evidenced from the recent phenomenology covering both inclusive and exclusive processes. We discuss a few fundamental issues of LFD that should be taken into account for the phenomenological applications. Using distinguished features of LFD, we obtain completely model-independent constraints for the light-front helicity amplitudes and present the consequences of these constraints in typical spin-system analyses such as in the elastic deuteron form factors and the N-Δ transition form factors. We also note the possible zero-mode complication in the form factor calculation of few-body systems and present a way of avoiding such complications.}, number={Jun 14 2004}, journal={NUCLEAR PHYSICS A}, author={Ji, CR}, year={2004}, month={Jun}, pages={255–259} }
@article{capolupo_ji_mishchenko_vitiello_2004, title={Phenomenology of flavor oscillations with non-perturbative effects from quantum field theory}, volume={594}, ISSN={["1873-2445"]}, DOI={10.1016/j.physletb.2004.05.016}, abstractNote={We analyze phenomenological aspects of the quantum field theoretical formulation of meson mixing and obtain the exact oscillation formula in the presence of the decay. This formula is different from quantum mechanical formula by additional high-frequency oscillation terms. In the infinite volume limit, the space of the flavor quantum states is unitarily inequivalent to the space of energy eigenstates.}, number={1-2}, journal={PHYSICS LETTERS B}, author={Capolupo, A and Ji, CR and Mishchenko, Y and Vitiello, G}, year={2004}, month={Jul}, pages={135–140} }
@article{carlson_ji_2003, title={Angular conditions, relations between the Breit and light-front frames, and subleading power corrections}, volume={67}, number={11}, journal={Physical Review. D, Particles and Fields}, author={Carlson, C. E. and Ji, C. R.}, year={2003}, pages={116002–1} }
@article{mishchenko_ji_2003, title={Molar mass estimate of dark matter from the dark mass distribution measurements}, volume={68}, ISSN={["2470-0029"]}, DOI={10.1103/physrevd.68.063503}, abstractNote={We study the distribution of dark matter versus visible matter using a set of data obtained from strong gravitational lensing in the galaxy cluster $\mathrm{CL}0024+1654$ and another set of data inferred from the universal rotation curves in spiral galaxies. The important feature of these two dramatically different observations is that the mass density profile of both visible and dark components can be estimated. From these measurements we deduce the mass of the dark matter particle and our estimate of the mass for the dark matter particle is ${\ensuremath{\mu}}_{d}\ensuremath{\approx}200--700\mathrm{MeV}.$ We contrast our estimates from $\mathrm{CL}0024+1654$ data and the universal rotation curves of the spiral galaxies and discuss their consistency.}, number={6}, journal={PHYSICAL REVIEW D}, author={Mishchenko, Y and Ji, CR}, year={2003}, month={Sep} }
@article{dewitt_choi_ji_2003, title={Radiative scalar meson decay in the light-front quark model}, volume={68}, ISSN={["2470-0029"]}, DOI={10.1103/physrevd.68.054026}, abstractNote={We construct a relativistic ${}^{3}{P}_{0}$ wave function for scalar mesons within the framework of the light-front quark model (LFQM). This scalar wave function is used to perform relativistic calculations of absolute widths for the radiative decay processes ${(0}^{++})\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma},$ ${(0}^{++})\ensuremath{\rightarrow}\ensuremath{\varphi}\ensuremath{\gamma},$ and ${(0}^{++})\ensuremath{\rightarrow}\ensuremath{\rho}\ensuremath{\gamma}$ which incorporate the effects of glueball-$q\overline{q}$ mixing. The mixed physical states are assumed to be ${f}_{0}(1370),$ ${f}_{0}(1500),$ and ${f}_{0}(1710)$ for which the flavor-glue content is taken from the mixing calculations of other works. Since experimental data for these processes are poor, our results are compared with those of a recent non-relativistic model calculation. We find that while the relativistic corrections introduced by the LFQM reduce the magnitudes of the decay widths by 50--70 %, the relative strengths between different decay processes are fairly well preserved. We also calculate decay widths for the processes $\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\varphi}}{(0}^{++})\ensuremath{\gamma}$ and ${(0}^{++})\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}$ involving the light scalars ${f}_{0}(980)$ and ${a}_{0}(980)$ to test the simple $q\overline{q}$ model of these mesons. Our results of the $q\overline{q}$ model for these processes are not consistent with well-established data, further supporting the idea that ${f}_{0}(980)$ and ${a}_{0}(980)$ are not conventional $q\overline{q}$ states.}, number={5}, journal={PHYSICAL REVIEW D}, author={DeWitt, MA and Choi, HM and Ji, CR}, year={2003}, month={Sep} }
@article{bakker_choi_ji_2003, title={Transition form factors between pseudoscalar and vector mesons in light-front dynamics}, volume={67}, number={11}, journal={Physical Review. D, Particles and Fields}, author={Bakker, B. L. G. and Choi, H. M. and Ji, C. R.}, year={2003}, pages={113007–1} }
@article{choi_ji_kisslinger_2002, title={Continuity of generalized parton distributions for the pion virtual Compton scattering}, volume={66}, number={5}, journal={Physical Review. D, Particles and Fields}, author={Choi, H. M. and Ji, C. R. and Kisslinger, L. S.}, year={2002}, pages={053011–1} }
@article{ji_choi_2002, title={Exploring timelike exclusive processes in the light-front approach}, volume={699}, DOI={10.1016/s0375-9474(01)01517-2}, abstractNote={We discuss a necessary nonvalence contribution in timelike exclusive processes. Utilizing a Schwinger-Dyson type of approach, we relate the nonvalence contribution to an ordinary light-front wave function that has been extensively tested in the spacelike exclusive processes. An application to $K_{\ell3}$ decays provides encouraging results.}, number={1-2}, journal={Nuclear Physics. A}, author={Ji, Chueng-Ryong and Choi, H. M.}, year={2002}, pages={344C–347} }
@article{bakker_ji_2002, title={Frame dependence of spin-one angular conditions in light front dynamics}, volume={65}, number={7}, journal={Physical Review. D, Particles and Fields}, author={Bakker, B. L. G. and Ji, C. R.}, year={2002}, pages={073002–1} }
@article{ji_mishchenko_2002, title={General theory of quantum field mixing}, volume={65}, number={9}, journal={Physical Review. D, Particles and Fields}, author={Ji, C. R. and Mishchenko, Y.}, year={2002}, pages={096015–1} }
@article{ji_choi_2002, title={Light-front QCD Hamiltonian dynamics and constituent quark picture in exclusive processes}, volume={108}, ISSN={["1873-3832"]}, DOI={10.1016/S0920-5632(02)01346-4}, abstractNote={After reviewing a connection between quantum chromodynamics and contituent quark model pictures in the light-front quantization with some comparison and contrast to the ordinary equal-time bridge a la Bogoliubov-Valatin transformation, we discuss some newer development of the light-front quark model phenomenology in exclusive processes including the embedded state. The skewed parton distribution appears to be a good testing ground for our new effective treatment of the light-front nonvalence contributions in timelike exclusive processes.}, number={2002 Apr}, journal={NUCLEAR PHYSICS B-PROCEEDINGS SUPPLEMENTS}, author={Ji, CR and Choi, HM}, year={2002}, month={Apr}, pages={288–292} }
@article{choi_ji_kisslinger_2002, title={Light-front quark model analysis of rare B -> Kl(+)l(-) decays}, volume={65}, number={7}, journal={Physical Review. D, Particles and Fields}, author={Choi, H. M. and Ji, C. R. and Kisslinger, L. S.}, year={2002}, pages={074032–1} }
@article{choi_kisslinger_ji_2002, title={Pion form factor and quark mass evolution in a light-front quark model}, volume={108}, ISSN={["1873-3832"]}, DOI={10.1016/S0920-5632(02)01351-8}, abstractNote={We discuss the soft contribution to the elastic pion form factor with the mass evolution from current to constituent quark being taken into account in a light-front quark model(LFQM).}, number={2002 Apr}, journal={NUCLEAR PHYSICS B-PROCEEDINGS SUPPLEMENTS}, author={Choi, HM and Kisslinger, LS and Ji, CR}, year={2002}, month={Apr}, pages={310–312} }
@article{bakker_choi_ji_2002, title={The vector meson form factor analysis in light-front dynamics}, volume={65}, number={11}, journal={Physical Review. D, Particles and Fields}, author={Bakker, B. L. G. and Choi, H. M. and Ji, C. R.}, year={2002}, pages={116001–1} }
@article{choi_ji_2001, title={Exploring the time-like region for the elastic form factor in the light-front quantization}, volume={679}, ISSN={["0375-9474"]}, DOI={10.1016/S0375-9474(00)00376-6}, abstractNote={Even though the Drell–Yan–West formulation is the most rigorous and well-established framework to compute the exclusive processes, its utility has been limited only to the space-like region because of the intrinsic kinematic constraint q+=0. We present an explicit example demonstrating how one may obtain the necessary information (i.e. nonvalence or so called Z-graph contribution) in the time-like region of exclusive process without encountering a formidable task of direct calculation that has hindered so far the progress in this area. In the analysis of qQ bound state form factors using an exactly solvable model of (3+1)-dimensional scalar field theory interacting with gauge fields, the results analytically continued from the space-like region coincide exactly with the direct results in the time-like region. This example verifies that the method of analytic continuation is capable of yielding the effect of complicate nonvalence contributions. The meson peaks analogous to the vector meson dominance (VMD) phenomena are also generated at the usual VMD positions.}, number={3-4}, journal={NUCLEAR PHYSICS A}, author={Choi, HM and Ji, CR}, year={2001}, month={Jan}, pages={735–750} }
@article{choi_ji_2001, title={Higher-Fock states and the covariance of the light-front quark model}, volume={16}, DOI={10.1142/S0217751X01006929}, abstractNote={The light-front quark model has been successful in describing various meson properties. We apply the model to the meson weak decays and discuss the covariance of the model. We find that the inclusion of the higher-Fock state (i.e. nonvalence or so called Z-graph) contributions is necessary to recover the covariance of the light-front quark model. We present the possibility of the effective calculation of the higher-Fock state contributions to restore the covariance in the light-front model.}, number={2001 Oct}, journal={International Journal of Modern Physics. A}, author={Choi, H. M. and Ji, Chueng-Ryong}, year={2001}, pages={357–359} }
@article{ji_maris_2001, title={K-13 transition form factors - art. no. 014032}, volume={6401}, number={1}, journal={Physical Review. D, Particles and Fields}, author={Ji, C. R. and Maris, P.}, year={2001}, pages={4032} }
@article{ji_choi_2001, title={New effective treatment of the light-front nonvalence contribution in timelike exclusive processes}, volume={513}, ISSN={["0370-2693"]}, DOI={10.1016/S0370-2693(01)00481-6}, abstractNote={We discuss a necessary nonvalence contribution in timelike exclusive processes. Following a Schwinger-Dyson type of approach, we relate the nonvalence contribution to an ordinary light-front wave function that has been extensively tested in the spacelike exclusive processes. A complicate four-body energy denominator is exactly cancelled in summing the light-front time-ordered amplitudes. Applying our method to $K_{\ell3}$ and $D^0\to K^- \ell^+ \nu_l$ where a rather substantial nonvalence contribution is expected, we find not only an improvement in comparing with the experimental data but also a covariance(i.e. frame-independence) of existing light-front constituent quark model.}, number={3-4}, journal={PHYSICS LETTERS B}, author={Ji, CR and Choi, HM}, year={2001}, month={Aug}, pages={330–336} }
@article{ji_mishchenko_2001, title={Nonperturbative vacuum effect in the quantum field theory of meson mixing - art. no. 076004}, volume={6407}, number={7}, journal={Physical Review. D, Particles and Fields}, author={Ji, C. R. and Mishchenko, Y.}, year={2001}, pages={6004-} }
@article{brodsky_hiller_ji_miller_2001, title={Perturbative QCD and factorization of coherent pionphoto production on the deuteron - art. no. 055204}, volume={6405}, number={5}, journal={Physical Review. C, Nuclear Physics}, author={Brodsky, S. J. and Hiller, J. R. and Ji, C. R. and Miller, G. A.}, year={2001}, pages={5204-} }
@article{kisslinger_choi_ji_2001, title={Pion form factor and quark mass evolution in a light-front Bethe-Salpeter model - art. no. 113005}, volume={6311}, number={11}, journal={Physical Review. D, Particles and Fields}, author={Kisslinger, L. S. and Choi, H. M. and Ji, C. R.}, year={2001}, pages={3005-} }
@article{ji_mitchell_2001, title={Poincare invariant algebra from instant to light-front quantization - art. no. 085013}, volume={6408}, number={8}, journal={Physical Review. D, Particles and Fields}, author={Ji, C. R. and Mitchell, C.}, year={2001}, pages={5013-} }
@article{bakker_choi_ji_2001, title={Regularizing the divergent structure of light-front currents -art. no. 074014}, volume={6307}, number={7}, journal={Physical Review. D, Particles and Fields}, author={Bakker, B. L. G. and Choi, H. M. and Ji, C. R.}, year={2001}, pages={4014} }
@article{ji_kim_min_2001, title={Rotation averaged dispersion relations in the light cone time-ordered perturbation theory - art. no. 025009}, volume={6402}, number={2}, journal={Physical Review. D, Particles and Fields}, author={Ji, C. R. and Kim, G. H. and Min, D. P.}, year={2001}, pages={5009-} }
@article{choi_ji_kisslinger_2001, title={Skewed quark distribution of the pion in the light-front quark model - art. no. 093006}, volume={6409}, number={9}, journal={Physical Review. D, Particles and Fields}, author={Choi, H. M. and Ji, C. R. and Kisslinger, L. S.}, year={2001}, pages={3006-} }
@article{ji_choi_2000, title={B-physics phenomenology with emphasis on the light-cone}, volume={90}, ISSN={["0920-5632"]}, DOI={10.1016/S0920-5632(00)00879-3}, abstractNote={Theoretical overviews on the B-physics are presented with an emphasis on the light-cone degrees of freedom. Our new treatment of the embedded states seems to give an encouraging result.}, number={2000 Dec}, journal={NUCLEAR PHYSICS B-PROCEEDINGS SUPPLEMENTS}, author={Ji, CR and Choi, HM}, year={2000}, month={Dec}, pages={93–99} }
@article{bakker_ji_2000, title={Disentangling intertwined embedded states and spin effects in light-front quantization - art. no. 074014}, volume={6207}, number={7}, journal={Physical Review. D, Particles and Fields}, author={Bakker, B. L. G. and Ji, C. R.}, year={2000}, pages={4014} }
@article{gubankova_ji_cotanch_2000, title={Flow equations for gluodynamics in the Coulomb gauge}, volume={62}, ISSN={["0556-2821"]}, DOI={10.1103/physrevd.62.074001}, abstractNote={A systematic procedure to consistently formulate a field theoretical, QCD bound state problem with a fixed number of constituents is outlined. The approach entails applying the Hamiltonian flow equations, which are a set of continuous unitary transformations, to a QCD motivated Hamiltonian with a confining interaction. The method is developed in detail for gluodynamics in the Coulomb gauge to obtain an effective block-diagonal Hamiltonian appropriate to a reduced Fock space with fixed number of dynamical gluons. Standard many-body techniques are used to numerically diagonalize this Hamiltonian in a constituent two gluon Fock space. The calculated gluon condensates and glueball masses are in good agreement with QCD sum rule and lattice results.}, number={7}, journal={PHYSICAL REVIEW D}, author={Gubankova, EL and Ji, CR and Cotanch, SR}, year={2000}, month={Oct} }
@article{gubankova_ji_cotanch_2000, title={Flow equations for quark-gluon interactions in light-front QCD}, volume={62}, ISSN={["0556-2821"]}, DOI={10.1103/physrevd.62.125012}, abstractNote={The flow-equation method of continuous unitary transformations is used to eliminate the minimal quark-gluon interaction in the light-front quantized QCD Hamiltonian. The coupled differential equations in the two lowest Fock sectors correspond to the renormalization of the light-front gluon mass and the generation of an effective quark-antiquark (as well as gluon-gluon) interaction. The original gauge field coupling is completely eliminated, even in the presence of degenerate states connected by this interaction. Further, a more singular ${1/q}^{4}$ behavior for the quark and gluon effective interactions at small gluon momenta is obtained, due to the asymptotic behavior of the effective gluon mass for small cutoff. We discuss the consequences of this asymptotic behavior and possible confinement implications.}, number={12}, journal={PHYSICAL REVIEW D}, author={Gubankova, E and Ji, CR and Cotanch, SR}, year={2000}, month={Dec} }
@article{ji_mitchell_2000, title={Frame independence of exclusive amplitudes In light-front quantization - art. no. 085020}, volume={6208}, number={8}, journal={Physical Review. D, Particles and Fields}, author={Ji, C. R. and Mitchell, C.}, year={2000}, pages={5020} }
@article{binger_ji_robertson_2000, title={Renormalization-scale-invariant PQCD predictions for R-e+(e)- and the Bjorken sum rule at next-to-leading order - art. no. 114011}, volume={6111}, number={11}, journal={Physical Review. D, Particles and Fields}, author={Binger, M. and Ji, C. R. and Robertson, D. G.}, year={2000}, pages={4011} }
@article{choi_ji_1999, title={Kaon electroweak form factors in the light-front quark model - art. no. 034001}, volume={5903}, number={3}, journal={Physical Review. D, Particles and Fields}, author={Choi, H. M. and Ji, C. R.}, year={1999}, pages={4001-} }
@article{arndt_ji_1999, title={Light-cone quark model analysis of radially excited pseudoscalar and vector mesons - art. no. 094020}, volume={6009}, number={9}, journal={Physical Review. D, Particles and Fields}, author={Arndt, D. and Ji, C. R.}, year={1999}, pages={4020} }
@article{choi_ji_1999, title={Light-front quark model analysis of exclusive 0(-) -> 0(-) semileptonic heavy meson decays}, volume={460}, ISSN={["1873-2445"]}, DOI={10.1016/S0370-2693(99)00817-5}, abstractNote={We present the analysis of exclusive $0^{-}$$\to$$0^{-}$ semileptonic heavy meson decays using the constituent quark model based on the light-front quantization. Our model is constrained by the variational principle for the well-known linear plus Coulomb interaction motivated by QCD. Our method of analytic continuation to obtain the weak form factors avoids the difficulty associated with the contribution from the nonvalence quark-antiquark pair creation. Our numerical results for the heavy-to-heavy and heavy-to-light meson decays are in a good agreement with the available experimental data and the lattice QCD results. In addition, our model predicts the two unmeasured mass spectra of $^{1}S_{0}(b\bar{b})$ and $^{3}S_{1}(b\bar{s})$ systems as $M_{b\bar{b}}$=9657 MeV and $M_{b\bar{s}}$= 5424 MeV.}, number={3-4}, journal={PHYSICS LETTERS B}, author={Choi, HM and Ji, CR}, year={1999}, month={Aug}, pages={461–466} }
@article{choi_ji_1999, title={Mixing angles and electromagnetic properties of ground state pseudoscalar and vector meson nonets in the light-cone quark model - art. no. 074015}, volume={5907}, number={7}, journal={Physical Review. D, Particles and Fields}, author={Choi, H. M. and Ji, C. R.}, year={1999}, pages={4015} }
@article{binger_ji_1999, title={Quantum held theory of meson mining - art. no. 056003}, volume={6005}, number={5}, journal={Physical Review. D, Particles and Fields}, author={Binger, M. and Ji, C. R.}, year={1999}, pages={6005} }
@article{robertson_swanson_szczepaniak_ji_cotanch_1999, title={Renormalized effective QCD Hamiltonian: Gluonic sector}, volume={59}, ISSN={["2470-0029"]}, DOI={10.1103/physrevd.59.074019}, abstractNote={Extending previous QCD Hamiltonian studies, we present a new renormalization procedure which generates an effective Hamiltonian for the gluon sector. The formulation is in the Coulomb gauge where the QCD Hamiltonian is renormalizable and the Gribov problem can be resolved. We utilize elements of the G\l{}azek and Wilson regularization method but now introduce a continuous cut-off procedure which eliminates non-local counterterms. The effective Hamiltonian is then derived to second order in the strong coupling constant. The resulting renormalized Hamiltonian provides a realistic starting point for approximate many-body calculations of hadronic properties for systems with explicit gluon degrees of freedom.}, number={7}, journal={PHYSICAL REVIEW D}, author={Robertson, DG and Swanson, ES and Szczepaniak, AP and Ji, CR and Cotanch, SR}, year={1999}, month={Apr} }
@misc{ji_binger_amiri_1998, title={Comment on "QCD fragmentation functions for B-c and B*(c) production"}, volume={57}, ISSN={["0556-2821"]}, DOI={10.1103/physrevd.57.7048}, abstractNote={For the inclusive production process of heavy pseudoscalar and vector mesons in ${e}^{+}{e}^{\ensuremath{-}}$ annihilation, we have improved the analytic calculation of the fragmentation function of heavy quarks up to ${\ensuremath{\tau}}^{2}\mathrm{ln}({\ensuremath{\tau}}^{2})$ where ${\ensuremath{\tau}}^{2}{=4m}^{2}/s,$ $m$ is the meson mass, and $s$ is the square of the total c.m. energy.}, number={11}, journal={PHYSICAL REVIEW D}, author={Ji, CR and Binger, M and Amiri, F}, year={1998}, month={Jun}, pages={7048–7049} }
@article{szczepaniak_ji_radyushkin_1998, title={Consistent analysis of O(alpha(s)) corrections to the pion elastic form factor}, volume={57}, ISSN={["0556-2821"]}, DOI={10.1103/physrevd.57.2813}, abstractNote={We examine the role of $O({\ensuremath{\alpha}}_{s})$ perturbative corrections to the pion elastic form factor ${F}_{\ensuremath{\pi}}{(Q}^{2})$. We express the quark current three-point function in terms of light cone variables and use Borel transformation to simultaneously model the Feynman mechanism contribution determined by the soft part of the pion light cone wave function and the hard term involving one gluon exchange. We find that for ${Q}^{2}\ensuremath{\sim}4{\mathrm{GeV}}^{2}$ the total $O({\ensuremath{\alpha}}_{s})$ contribution may reach $30%$ of the soft contribution, even though its hard, factorization scale dependent part remains rather small.}, number={5}, journal={PHYSICAL REVIEW D}, author={Szczepaniak, A and Ji, CR and Radyushkin, A}, year={1998}, month={Mar}, pages={2813–2822} }
@article{ji_min_1998, title={Cooling modes of neutron stars}, volume={57}, ISSN={["1550-2368"]}, DOI={10.1103/physrevd.57.5963}, abstractNote={The direct Urca process is studied in the presence of kaon condensation. We consider the contributions from both strange and nonstrange hadrons. Our calculations indicate that the role of hyperons is as important as the role of nonstrange nucleons in the cooling mechanism of neutron stars. We also find that the temperature dependence of the weak neutral current contribution is given by ${T}^{7}$, which intermediates between the direct Urca process of ${T}^{6}$ and the modified Urca process of ${T}^{8}$.}, number={10}, journal={PHYSICAL REVIEW D}, author={Ji, CR and Min, DP}, year={1998}, month={May}, pages={5963–5969} }
@article{ji_kaminski_lesniak_szczepaniak_williams_1998, title={Coupled channel analysis of S-wave pi pi and (K)over-barK photoproduction}, volume={58}, ISSN={["1089-490X"]}, DOI={10.1103/physrevc.58.1205}, abstractNote={We present a coupled channel partial wave analysis of nondiffractive $S$-wave ${\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ and ${K}^{+}{K}^{\ensuremath{-}}$ photoproduction focusing on the $K\overline{K}$ threshold. Final state interactions are included. We calculate total cross sections and angular and effective mass distributions in both $\ensuremath{\pi}\ensuremath{\pi}$ and $K\overline{K}$ channels. Our results indicate that these processes are experimentally measurable and valuable information on the ${f}_{0}$(980) resonance structure can be obtained.}, number={2}, journal={PHYSICAL REVIEW C}, author={Ji, CR and Kaminski, R and Lesniak, L and Szczepaniak, A and Williams, R}, year={1998}, month={Aug}, pages={1205–1217} }
@article{ji_choi_1998, title={Mixing angles and electromagnetic properties of ground statepseudoscalar and vector meson nonets in the light-cone quarkmodel}, volume={29}, number={11}, journal={Acta Physica Polonica. B}, author={Ji, C. R. and Choi, H. M.}, year={1998}, pages={3363–3366} }
@article{choi_ji_1998, title={Nonvanishing zero modes in the light-front current - art. no.071901}, volume={5807}, number={7}, journal={Physical Review. D, Particles and Fields}, author={Choi, H. M. and Ji, C. R.}, year={1998}, pages={1901} }
@article{brodsky_ji_pang_robertson_1998, title={Optimal renormalization scale and scheme for exclusive processes}, volume={57}, ISSN={["0556-2821"]}, DOI={10.1103/physrevd.57.245}, abstractNote={We use the Brodsky-Lepage-Mackenzie (BLM) method to fix the renormalization scale of the QCD coupling in exclusive hadronic amplitudes such as the pion form factor and the photon-to-pion transition form factor at large momentum transfer. Renormalization-scheme-independent commensurate scale relations are established which connect the hard scattering subprocess amplitudes that control exclusive processes to other QCD observables such as the heavy quark potential and the electron-positron annihilation cross section. The commensurate scale relation connecting the heavy quark potential, as determined from lattice gauge theory, to the photon-to-pion transition form factor is in excellent agreement with $\ensuremath{\gamma}\stackrel{\ensuremath{\rightarrow}}{e}{\ensuremath{\pi}}^{0}e$ data assuming that the pion distribution amplitude is close to its asymptotic form $\sqrt{3}{f}_{\ensuremath{\pi}}x(1\ensuremath{-}x)$. We also reproduce the scaling and normalization of the $\ensuremath{\gamma}\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\gamma}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ data at large momentum transfer. Because the renormalization scale is small, we argue that the effective coupling is nearly constant, thus accounting for the nominal scaling behavior of the data. However, the normalization of the space-like pion form factor ${F}_{\ensuremath{\pi}}{(Q}^{2})$ obtained from electroproduction experiments is somewhat higher than that predicted by the corresponding commensurate scale relation. This discrepancy may be due to systematic errors introduced by the extrapolation of the ${\ensuremath{\gamma}}^{*}\stackrel{\ensuremath{\rightarrow}}{p}{\ensuremath{\pi}}^{+}n$ electroproduction data to the pion pole.}, number={1}, journal={PHYSICAL REVIEW D}, author={Brodsky, SJ and Ji, CR and Pang, A and Robertson, DG}, year={1998}, month={Jan}, pages={245–252} }
@article{cotanch_szczepaniak_swanson_ji_1998, title={QCD Hamiltonian approach for the glueball spectrum}, volume={631}, DOI={10.1016/s0375-9474(98)00082-7}, abstractNote={A new, comprehensive relativistic many-body approach utilizing the Coulomb gauge QCD Hamiltonian is advanced for hadron physics. The formalism properly incoporates renormalization for regularizing divergences and also manifests the Nambu-Goldstone realization of chiral symmetry. Using standard many-body techniques, calculations for the constitutuent quark, gluon condensates and masses and gluon spectrum are found to be in good agreement with QCD sum-rules and quenched lattice gauge results.}, number={1998 Mar. 2}, journal={Nuclear Physics. A}, author={Cotanch, S. R. and Szczepaniak, A. P. and Swanson, E. S. and Ji, Chueng-Ryong}, year={1998}, pages={C640–643} }
@book{qcd, lightcone physics and hadron phenomenology_1998, ISBN={981023385X}, publisher={Singapore; River Edge, NJ: World Scientific}, year={1998} }
@article{ji_kim_min_1998, title={Rotation average in light cone time-ordered perturbation theory- art. no. 105020}, volume={5810}, number={10}, journal={Physical Review. D, Particles and Fields}, author={Ji, C. R. and Kim, G. H. and Min, D. P.}, year={1998}, pages={5020} }
@article{ji_pang_1997, title={Going beyond the peaking approximation in the PQCD analysis of exclusive heavy meson pair production}, volume={55}, ISSN={["0556-2821"]}, DOI={10.1103/physrevd.55.1253}, abstractNote={In the PQCD analyses of the exclusive production of higher generation hadrons, the quark distribution amplitude of the heavy quark system has often been approximated by a \ensuremath{\delta} function from the nonrelativistic consideration. Going beyond the peaking approximation, the factorization of the covariant hard scattering amplitude from the nonperturbative quark distribution amplitude is no longer valid. We therefore use the light-cone time-ordered perturbation theory which is the step prior to the usual factorization formula and calculate the form factor of a pseudoscalar meson composed of a heavy quark and antiquark. However, we find that the numerical results for the cross section of exclusive heavy meson pair production in ${e}^{+}{e}^{\ensuremath{-}}$ annihilation are not much different from those of the peaking approximation.}, number={3}, journal={PHYSICAL REVIEW D}, author={Ji, CR and Pang, A}, year={1997}, month={Feb}, pages={1253–1256} }
@article{choi_ji_1997, title={Light-cone quark model predictions for radiative meson decays}, volume={618}, ISSN={["0375-9474"]}, DOI={10.1016/S0375-9474(97)00052-3}, abstractNote={We investigate the radiative decay of pseudoscalar (π, K, η, η′), vector (ϱ, K∗, ω, ƒ) and axial-vector (A1) mesons using a simple relativistic constituent quark model. For both simplicity and relativity, we take advantage of the distinguished features in the light-cone quantization method: (1) the Fock state expansion of meson wave functions are not contaminated by the vacuum fluctuation, (2) the problem of assigning quantum numbers JPC to mesons is circumvented by the Melosh transformation. Except the well-known constituent quark masses of (u, d, s) quarks and the spin-averaged meson masses, the only parameter in the model is the Gaussian parameter β which determines the broadness (or sharpness) of the radial wave function. Our overall predictions of pseudoscalar, vector and axial-vector meson radiative decay processes are in remarkably good agreement with the experimental data.}, number={3}, journal={NUCLEAR PHYSICS A}, author={Choi, HM and Ji, CR}, year={1997}, month={Jun}, pages={291–316} }
@article{choi_ji_1997, title={Relations among the light-cone quark models with the invariant meson mass scheme and the model prediction of the eta-eta' mixing angle}, volume={56}, ISSN={["0556-2821"]}, DOI={10.1103/physrevd.56.6010}, abstractNote={We analyze the relations among the light-cone quark models which are based on the invariant meson mass scheme. We find that the difference from the Jacobi factor in model wave functions is substantially reduced in the numerical predictions for the physical observables once the best fit parameters are chosen. The difference in the choice of radial wave function [e.g., harmonic oscillator (HO) wave function versus power-law wave function] is, however, still appreciable even though the best fit parameters are used. We also observe an excellent agreement between the HO model predictions and the experimental data on the radiative decays of pseudoscalar $(P)$ and vector $(V)$ mesons and $P\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}$ processes, if we use the constraint obtained by the axial anomaly plus partial conservation of axial-vector current relations and choose the $\ensuremath{\eta}\ensuremath{-}{\ensuremath{\eta}}^{\ensuremath{'}}$ mixing angle ${\ensuremath{\theta}}_{\mathrm{SU}(3)}$ $\ensuremath{\approx}\ensuremath{-}19\ifmmode^\circ\else\textdegree\fi{}.$}, number={9}, journal={PHYSICAL REVIEW D}, author={Choi, HM and Ji, CR}, year={1997}, month={Nov}, pages={6010–6013} }