@article{froustey_richers_grohs_flynn_foucart_kneller_mclaughlin_2024, title={Neutrino fast flavor oscillations with moments: Linear stability analysis and application to neutron star mergers}, volume={109}, ISSN={["2470-0029"]}, DOI={10.1103/PhysRevD.109.043046}, abstractNote={Providing an accurate modeling of neutrino physics in dense astrophysical environments such as binary neutron star mergers presents a challenge for hydrodynamic simulations. Nevertheless, understanding how flavor transformation can occur and affect the dynamics, the mass ejection, and the nucleosynthesis will need to be achieved in the future. Computationally expensive, large-scale simulations frequently evolve the first classical angular moments of the neutrino distributions. By promoting these quantities to matrices in flavor space, we develop a linear stability analysis of fast flavor oscillations using only the first two ``quantum'' moments, which notably requires generalizing the classical closure relations that appropriately truncate the hierarchy of moment equations in order to treat quantum flavor coherence. After showing the efficiency of this method on a well-understood test situation, we perform a systematic search of the occurrence of fast flavor instabilities in a neutron star merger simulation. We discuss the successes and shortcomings of moment linear stability analysis, as this framework provides a time-efficient way to design and study better closure prescriptions in the future.}, number={4}, journal={PHYSICAL REVIEW D}, author={Froustey, Julien and Richers, Sherwood and Grohs, Evan and Flynn, Samuel D. and Foucart, Francois and Kneller, James P. and McLaughlin, Gail C.}, year={2024}, month={Feb} }
 @article{grohs_richers_couch_foucart_froustey_kneller_mclaughlin_2024, title={Two-moment Neutrino Flavor Transformation with Applications to the Fast Flavor Instability in Neutron Star Mergers}, volume={963}, ISSN={["1538-4357"]}, DOI={10.3847/1538-4357/ad13f2}, abstractNote={
 Multi-messenger astrophysics has produced a wealth of data with much more to come in the future. This enormous data set will reveal new insights into the physics of core-collapse supernovae, neutron star mergers, and many other objects where it is actually possible, if not probable, that new physics is in operation. To tease out different possibilities, we will need to analyze signals from photons, neutrinos, gravitational waves, and chemical elements. This task is made all the more difficult when it is necessary to evolve the neutrino component of the radiation field and associated quantum-mechanical property of flavor in order to model the astrophysical system of interest—a numerical challenge that has not been addressed to this day. In this work, we take a step in this direction by adopting the technique of angular-integrated moments with a truncated tower of dynamical equations and a closure, convolving the flavor-transformation with spatial transport to evolve the neutrino radiation quantum field. We show that moments capture the dynamical features of fast flavor instabilities in a variety of systems, although our technique is by no means a universal blueprint for solving fast flavor transformation. To evaluate the effectiveness of our moment results, we compare to a more precise particle-in-cell method. Based on our results, we propose areas for improvement and application to complementary techniques in the future.}, number={1}, journal={ASTROPHYSICAL JOURNAL}, author={Grohs, Evan and Richers, Sherwood and Couch, Sean M. and Foucart, Francois and Froustey, Julien and Kneller, James P. and McLaughlin, Gail C.}, year={2024}, month={Mar} }
 @article{grohs_richers_couch_foucart_kneller_mclaughlin_2023, title={Neutrino fast flavor instability in three dimensions for a neutron star merger}, volume={846}, ISSN={["1873-2445"]}, DOI={10.1016/j.physletb.2023.138210}, abstractNote={The flavor evolution of neutrinos in core collapse supernovae and neutron star mergers is a critically important unsolved problem in astrophysics. Following the electron flavor evolution of the neutrino system is essential for calculating the thermodynamics of compact objects as well as the chemical elements they produce. Accurately accounting for flavor transformation in these environments is challenging for a number of reasons, including the large number of neutrinos involved, the small spatial scale of the oscillation, and the nonlinearity of the system. We take a step in addressing these issues by presenting a method which describes the neutrino fields in terms of angular moments. We apply our moment method to neutron star merger conditions and show it simulates fast flavor neutrino transformation in a region where this phenomenon is expected to occur. By comparing with particle-in-cell calculations we show that the moment method is able to capture the three phases of growth, saturation, and decoherence, and correctly predicts the lengthscale of the fastest growing fluctuations in the neutrino field.}, journal={PHYSICS LETTERS B}, author={Grohs, Evan and Richers, Sherwood and Couch, Sean M. and Foucart, Francois and Kneller, James P. and McLaughlin, G. C.}, year={2023}, month={Nov} }
 @article{baxter_benzvi_bonivento_brazier_clark_coleiro_collom_colomer-molla_cousins_orellana_et al._2022, title={Collaborative experience between scientific software projects using Agile Scrum development}, volume={7}, ISSN={["1097-024X"]}, DOI={10.1002/spe.3120}, abstractNote={Developing sustainable software for the scientific community requires expertise in software engineering and domain science. This can be challenging due to the unique needs of scientific software, the insufficient resources for software engineering practices in the scientific community, and the complexity of developing for evolving scientific contexts. While open‐source software can partially address these concerns, it can introduce complicating dependencies and delay development. These issues can be reduced if scientists and software developers collaborate. We present a case study wherein scientists from the SuperNova Early Warning System collaborated with software developers from the Scalable Cyberinfrastructure for Multi‐Messenger Astrophysics project. The collaboration addressed the difficulties of open‐source software development, but presented additional risks to each team. For the scientists, there was a concern of relying on external systems and lacking control in the development process. For the developers, there was a risk in supporting a user‐group while maintaining core development. These issues were mitigated by creating a second Agile Scrum framework in parallel with the developers' ongoing Agile Scrum process. This Agile collaboration promoted communication, ensured that the scientists had an active role in development, and allowed the developers to evaluate and implement the scientists' software requirements. The collaboration provided benefits for each group: the scientists actuated their development by using an existing platform, and the developers utilized the scientists' use‐case to improve their systems. This case study suggests that scientists and software developers can avoid scientific computing issues by collaborating and that Agile Scrum methods can address emergent concerns.}, journal={SOFTWARE-PRACTICE & EXPERIENCE}, author={Baxter, Amanda L. and BenZvi, Segev Y. and Bonivento, Walter and Brazier, Adam and Clark, Michael and Coleiro, Alexis and Collom, David and Colomer-Molla, Marta and Cousins, Bryce and Orellana, Aliwen Delgado and et al.}, year={2022}, month={Jul} }
 @article{baxter_benzvi_jaimes_coleiro_molla_dornic_goldhagen_graf_griswold_habig_et al._2022, title={SNEWPY: A Data Pipeline from Supernova Simulations to Neutrino Signals}, volume={925}, ISSN={["1538-4357"]}, DOI={10.3847/1538-4357/ac350f}, abstractNote={Current neutrino detectors will observe hundreds to thousands of neutrinos from Galactic supernovae, and future detectors will increase this yield by an order of magnitude or more. With such a data set comes the potential for a huge increase in our understanding of the explosions of massive stars, nuclear physics under extreme conditions, and the properties of the neutrino. However, there is currently a large gap between supernova simulations and the corresponding signals in neutrino detectors, which will make any comparison between theory and observation very difficult. SNEWPY is an open-source software package that bridges this gap. The SNEWPY code can interface with supernova simulation data to generate from the model either a time series of neutrino spectral fluences at Earth, or the total time-integrated spectral fluence. Data from several hundred simulations of core-collapse, thermonuclear, and pair-instability supernovae is included in the package. This output may then be used by an event generator such as sntools or an event rate calculator such as the SuperNova Observatories with General Long Baseline Experiment Simulator (SNOwGLoBES). Additional routines in the SNEWPY package automate the processing of the generated data through the SNOwGLoBES software and collate its output into the observable channels of each detector. In this paper we describe the contents of the package, the physics behind SNEWPY, the organization of the code, and provide examples of how to make use of its capabilities.}, number={2}, journal={ASTROPHYSICAL JOURNAL}, author={Baxter, Amanda L. and BenZvi, Segev and Jaimes, Joahan Castaneda and Coleiro, Alexis and Molla, Marta Colomer and Dornic, Damien and Goldhagen, Tomer and Graf, Anne and Griswold, Spencer and Habig, Alec and et al.}, year={2022}, month={Feb} }
 @misc{al kharusi_benzvi_bobowski_bonivento_brdar_brunner_caden_clark_coleiro_colomer-molla_et al._2021, title={SNEWS 2.0: a next-generation supernova early warning system for multi-messenger astronomy}, volume={23}, ISSN={["1367-2630"]}, DOI={10.1088/1367-2630/abde33}, abstractNote={The next core-collapse supernova in the Milky Way or its satellites will represent a once-in-a-generation opportunity to obtain detailed information about the explosion of a star and provide significant scientific insight for a variety of fields because of the extreme conditions found within. Supernovae in our galaxy are not only rare on a human timescale but also happen at unscheduled times, so it is crucial to be ready and use all available instruments to capture all possible information from the event. The first indication of a potential stellar explosion will be the arrival of a bright burst of neutrinos. Its observation by multiple detectors worldwide can provide an early warning for the subsequent electromagnetic fireworks, as well as signal to other detectors with significant backgrounds so they can store their recent data. The supernova early warning system (SNEWS) has been operating as a simple coincidence between neutrino experiments in automated mode since 2005. In the current era of multi-messenger astronomy there are new opportunities for SNEWS to optimize sensitivity to science from the next galactic supernova beyond the simple early alert. This document is the product of a workshop in June 2019 towards design of SNEWS 2.0, an upgraded SNEWS with enhanced capabilities exploiting the unique advantages of prompt neutrino detection to maximize the science gained from such a valuable event.}, number={3}, journal={NEW JOURNAL OF PHYSICS}, author={Al Kharusi, S. and BenZvi, S. Y. and Bobowski, J. S. and Bonivento, W. and Brdar, V and Brunner, T. and Caden, E. and Clark, M. and Coleiro, A. and Colomer-Molla, M. and et al.}, year={2021}, month={Mar} }
 @article{stapleford_froehlich_kneller_2020, title={Coupling neutrino oscillations and simulations of core-collapse supernovae}, volume={102}, ISSN={["1550-2368"]}, url={http://dx.doi.org/10.1103/physrevd.102.081301}, DOI={10.1103/PhysRevD.102.081301}, abstractNote={At the present time even the most sophisticated, multi-dimensional simulations of core-collapse supernovae do not (self-consistently) include neutrino flavor transformation. This physics is missing despite the importance of neutrinos in the core-collapse explosion paradigm. Because of this dependence, any flavor transformation that occurs in the region between the proto-neutron star and the shock could result in major effects upon the dynamics of the explosion. We present the first hydrodynamic core-collapse supernova simulation which simultaneously includes flavor transformation of the free-streaming neutrinos in the neutrino transport. These oscillation calculations are dynamically updated and evolve self-consistently alongside the hydrodynamics. Using a $M=20\;{\rm M_{\odot}}$ progenitor, we find that while the oscillations have an effect on the neutrino emission and the heating rates, flavor transformation alone does not lead to a successful explosion of this progenitor in spherical symmetry.}, number={8}, journal={PHYSICAL REVIEW D}, publisher={American Physical Society (APS)}, author={Stapleford, Charles J. and Froehlich, Carla and Kneller, James P.}, year={2020}, month={Oct} }
 @article{isotropicsqa_2019, DOI={10.5281/zenodo.2574231}, journal={Zenodo}, year={2019}, month={Feb} }
 @article{isotropicsqa_2019, DOI={10.5281/zenodo.2574232}, journal={Zenodo}, year={2019}, month={Feb} }
 @article{isotropicsqa_2019, DOI={10.5281/zenodo.3236833}, journal={Zenodo}, year={2019}, month={Feb} }
 @misc{neutrino quantum kinetics in compact objects_2019, DOI={10.5281/zenodo.2574228}, abstractNote={This contains the codebase and data from "Neutrino Quantum Kinetics in Compact Objects" by Sherwood Richers, Gail McLaughlin, Alexey Vlasenko, and James P. Kneller. (2019, submitted to PRD) ======================<br> All f.h5 file contents<br> ======================<br> r(cm) - proxy for the time (r=ct)<br> dr_block(cm) - proxy for the block timestep (dr=cdt). Stored for recovery purposes<br> dr_int(cm) - proxy for the interaction integration timestep (dr=cdt). Stored for recovery purposes.<br> dr_osc(cm) - proxy for the oscillation integration timestep (dr=cdt). Stored for recovery purposes.<br> fmatrixf - dimensionless distribution function. Accessed with [time][helicity][energy][flavor1][flavor2][0=real,1=imaginary] ==================<br> Directory contents<br> ================== fiducial - simulation output from the fiducial case of a background<br> with rho=1e10g/ccm, T=10MeV, Ye=0.3, the HShen EOS, including<br> oscillations, neutrino absorption on nucleons and nuclei, inelastic<br> electron scattering, elastic nucleon scattering, electron-positron<br> pair production, effective-absorption nucleon-nucleon bremsstrahlung,<br> and neutrino-neutrino scattering and pair processes. Using 25 energy<br> bins covering up to 100 MeV. noosc_full - simulation output from the fiducial case with the same<br> circumstanses as above, except without oscillations and using 50<br> energy bins up to 100 MeV. *_tdecohere_times.dat - decoherence time (col. 4) for neutrinos at<br> every radial point (col. 1), each helicity<br> (col. 2), and every energy (col. 3). noosc_supernova_background.dat - snapshot from a 1D core-collapse<br> supernova simulation. The only relevant<br> quantities are the radius (col. 2), density<br> (col. 3), electron fraction (col. 4),<br> temperature (col. 5), electron chemical<br> potential (col. 9), proton chemical potential<br> (col. 10), and neutron chemical potential<br> (col. 11) sn_decoherence_full - calculations done including the full set of<br> collision interactions listed in fiducial,<br> using 25 energy bins spanning the appropriate<br> domain. sn_decoherence_nonu4 - calculations done including the full set of<br> collision interactions listed in fiducial<br> except neutrino-neutrino scattering and pair<br> processes, using 200 energy bins spanning a<br> domain of 200 MeV.}, journal={Zenodo}, year={2019}, month={Feb} }
 @misc{neutrino quantum kinetics in compact objects_2019, DOI={10.5281/zenodo.2574227}, abstractNote={This contains the codebase and data from "Neutrino Quantum Kinetics in<br> Compact Objects" by Sherwood Richers, Gail McLaughlin, Alexey<br> Vlasenko, and James P. Kneller. (2019, submitted to PrD) ======================<br> All f.h5 file contents<br> ======================<br> r(cm) - proxy for the time (r=ct)<br> dr_block(cm) - proxy for the block timestep (dr=cdt). Stored for<br> recovery purposes<br> dr_int(cm) - proxy for the interaction integration timestep<br> (dr=cdt). Stored for recovery purposes.<br> dr_osc(cm) - proxy for the oscillation integration timestep<br> (dr=cdt). Stored for recovery purposes.<br> fmatrixf - dimensionless distribution function. Accessed with<br> [time][helicity][energy][flavor1][flavor2][0=real,1=imaginary] ==================<br> Directory contents<br> ================== fiducial - simulation output from the fiducial case of a background<br> with rho=1e10g/ccm, T=10MeV, Ye=0.3, the HShen EOS, including<br> oscillations, neutrino absorption on nucleons and nuclei, inelastic<br> electron scattering, elastic nucleon scattering, electron-positron<br> pair production, effective-absorption nucleon-nucleon bremsstrahlung,<br> and neutrino-neutrino scattering and pair processes. Using 25 energy<br> bins covering up to 100 MeV. noosc_full - simulation output from the fiducial case with the same<br> circumstanses as above, except without oscillations and using 50<br> energy bins up to 100 MeV. noosc_supernova_background.dat - snapshot from a 1D core-collapse<br> supernova simulation. The only relevant<br> quantities are the radius (col. 2), density<br> (col. 3), electron fraction (col. 4),<br> temperature (col. 5), electron chemical<br> potential (col. 9), proton chemical potential<br> (col. 10), and neutron chemical potential<br> (col. 11)<br> <br> noosc_*_tdecohere.dat - decoherence time (col. 4) for neutrinos at<br> every radial point (col. 1), each helicity<br> (col. 2), and every energy (col. 3), using 50<br> energy bins at integer multiples of 2 MeV. full - calculations done including the full set of<br> collision interactions listed in fiducial. nonu4 - calculations done including the full set of<br> collision interactions listed in fiducial<br> except neutrino-neutrino scattering/pair<br> processes.}, journal={Zenodo}, year={2019}, month={Feb} }
 @misc{neutrino quantum kinetics in compact objects_2019, DOI={10.5281/zenodo.3237245}, abstractNote={This contains the codebase and data from "Neutrino Quantum Kinetics in<br> Compact Objects" by Sherwood Richers, Gail McLaughlin, Alexey<br> Vlasenko, and James P. Kneller. (2019, submitted to PrD) ======================<br> All f.h5 file contents<br> ======================<br> r(cm) - proxy for the time (r=ct)<br> dr_block(cm) - proxy for the block timestep (dr=cdt). Stored for<br> recovery purposes<br> dr_int(cm) - proxy for the interaction integration timestep<br> (dr=cdt). Stored for recovery purposes.<br> dr_osc(cm) - proxy for the oscillation integration timestep<br> (dr=cdt). Stored for recovery purposes.<br> fmatrixf - dimensionless distribution function. Accessed with<br> [time][helicity][energy][flavor1][flavor2][0=real,1=imaginary] ==================<br> Directory contents<br> ================== fiducial - simulation output from the fiducial case of a background<br> with rho=1e10g/ccm, T=10MeV, Ye=0.3, the HShen EOS, including<br> oscillations, neutrino absorption on nucleons and nuclei, inelastic<br> electron scattering, elastic nucleon scattering, electron-positron<br> pair production, effective-absorption nucleon-nucleon bremsstrahlung,<br> and neutrino-neutrino scattering and pair processes. Using 25 energy<br> bins covering up to 100 MeV. noosc_full - simulation output from the fiducial case with the same<br> circumstanses as above, except without oscillations and using 50<br> energy bins up to 100 MeV. noosc_supernova_background.dat - snapshot from a 1D core-collapse<br> supernova simulation. The only relevant<br> quantities are the radius (col. 2), density<br> (col. 3), electron fraction (col. 4),<br> temperature (col. 5), electron chemical<br> potential (col. 9), proton chemical potential<br> (col. 10), and neutron chemical potential<br> (col. 11)<br> <br> noosc_*_tdecohere.dat - decoherence time (col. 4) for neutrinos at<br> every radial point (col. 1), each helicity<br> (col. 2), and every energy (col. 3), using 50<br> energy bins at integer multiples of 2 MeV. full - calculations done including the full set of<br> collision interactions listed in fiducial. nonu4 - calculations done including the full set of<br> collision interactions listed in fiducial<br> except neutrino-neutrino scattering/pair<br> processes.}, journal={Zenodo}, year={2019}, month={Feb} }
 @article{richers_mclaughlin_kneller_vlasenko_2019, title={Neutrino quantum kinetics in compact objects}, volume={99}, ISSN={["2470-0029"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85068983479&partnerID=MN8TOARS}, DOI={10.1103/PhysRevD.99.123014}, abstractNote={Neutrinos play a critical role of transporting energy and changing the lepton density within core-collapse supernovae and neutron star mergers. The quantum kinetic equations (QKEs) combine the effects of neutrino-matter interactions treated in classical Boltzmann transport with the neutrino flavor-changing effects treated in neutrino oscillation calculations. We present a method for extending existing neutrino interaction rates to full QKE source terms for use in numerical calculations. We demonstrate the effects of absorption and emission by nucleons and nuclei, electron scattering, electron-positron pair annihilation, nucleon-nucleon bremsstrahlung, neutrino-neutrino scattering. For the first time, we include all these collision terms self-consistently in a simulation of the full isotropic QKEs in conditions relevant to core-collapse supernovae and neutron star mergers. For our choice of parameters, the long-term evolution of the neutrino distribution function proceeds similarly with and without the oscillation term, though with measurable differences. We demonstrate that electron scattering, nucleon-nucleon bremsstrahlung processes, and four-neutrino processes dominate flavor decoherence in the protoneutron star (PNS), absorption dominates near the shock, and all of the considered processes except elastic nucleon scattering are relevant in the decoupling region. Finally, we propose an effective decoherence opacity that at most energies predicts decoherence rates to within a factor of 10 in our model PNS and within 20% outside of the PNS.}, number={12}, journal={PHYSICAL REVIEW D}, publisher={American Physical Society (APS)}, author={Richers, Sherwood A. and McLaughlin, Gail C. and Kneller, James P. and Vlasenko, Alexey}, year={2019}, month={Jun} }
 @inproceedings{neutrinos from pair instability supernovae_2019, volume={219}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85071955177&partnerID=MN8TOARS}, DOI={10.1007/978-3-030-13876-9_25}, abstractNote={We present the first ever calculations of the neutrino signal from pair-instability supernovae (PISNe) using two hydrodynamical simulations which bracket the mass range of the stars which explode via this mechanism. We take into account both the time and energy dependence of the emission and the flavor oscillations, as well as investigating the equation-of-state dependence. We then process the computed neutrino fluxes at Earth through four different neutrino detectors. We show how the neutrino signal from PISNe possesses unique features that distinguish it from other supernovae, how the detectors we consider are capable of observing neutrinos from PISNe at the standard distance of 10 kpc, and how the proposed HyperKamiokande detector can even reach the Large Magellanic Cloud and the several very high mass stars known to exist there.}, booktitle={Springer Proceedings in Physics}, year={2019}, pages={151–155} }
 @article{wright_kneller_2018, title={Feasibility of using neutrino intensity interferometry to measure protoneutron star radii}, volume={98}, ISSN={["2470-0029"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85052648061&partnerID=MN8TOARS}, DOI={10.1103/PhysRevD.98.043016}, abstractNote={It has recently been demonstrated analytically that the two-point correlation function for pairs of neutrinos may contain information about the size of the protoneutron star formed in a Galactic core-collapse supernova. The information about the size of the source emerges via the neutrino equivalent of intensity interferometry originally used by Hanbury-Brown and Twiss with photons to measure the radii of stars. However the analytic demonstration of neutrino intensity interferometry with supernova neutrinos made a number of approximations: that the two neutrinos had equal energies, that the neutrinos were emitted at simultaneous times from two points and that they were detected simultaneously at two detection points that formed a plane with the emission points. These approximations need to be relaxed in order to better determine the feasibility of neutrino intensity interferometry for supernovae neutrinos in a more realistic scenario. In this paper we further investigate the feasibility of intensity interferometry for supernova neutrinos by relaxing all the approximations made in the earlier study. We find that, while relaxing any one assumption reduces the correlation signal, the relaxation of the assumption of equal times of detection is by far the largest detrimental factor. For neutrino energies of order ∼15  MeV and a supernova distance of L=10  kpc, we show that in order to observe the interference pattern in the two-point correlation function of the neutrino pairs, the timing resolution of a detector needs to be on the order of ≲10-21  s if the initial neutrino wave packet has a size of σx∼10-11  cm.}, number={4}, journal={PHYSICAL REVIEW D}, author={Wright, Warren P. and Kneller, James P.}, year={2018}, month={Aug} }
 @inproceedings{kneller_2018, title={Neutrino flavor transformation in supernova as a probe for nonstandard neutrino-scalar interactions}, volume={341}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85079340911&partnerID=MN8TOARS}, booktitle={Proceedings of Science}, author={Kneller, J.P.}, year={2018} }
 @article{yang_kneller_2018, title={Neutrino flavor transformation in supernovae as a probe for nonstandard neutrino-scalar interactions}, volume={97}, ISSN={["2470-0029"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85048113006&partnerID=MN8TOARS}, DOI={10.1103/physrevd.97.103018}, abstractNote={We explore the possibility of probing the nonstandard interactions between the neutrino and a hypothetical massive scalar or pseudoscalar via neutrino flavor transformation in supernovae. We find that in ultrarelativistic limit, the effective interaction between the neutrinos does not vanish if neutrinos are Majorana fermions but does vanish if neutrinos are Dirac fermions. The impact of the new neutrino interaction upon the flavor transformation above the neutrinosphere has been calculated in the context of the multi-angle "neutrino bulb model" and we find that the addition of the nonstandard neutrino self-interaction (NSSI) to the ordinary V-A self-interaction between neutrinos is capable of dramatically altering the collective oscillation when its strength is comparable to the standard, V-A, interaction. The effect of flavor-preserving (FP) NSSI is generally to suppress flavor transformation, while the flavor-violating (FV) components are found to promote flavor transformations. The neutrino signal from a Galactic supernova can provide complimentary constraints on scalar/pseudoscalar interactions of neutrinos as well as distinguishing whether the neutrino is a Majorana or Dirac fermion.}, number={10}, journal={PHYSICAL REVIEW D}, author={Yang, Yue and Kneller, James P.}, year={2018}, month={May} }
 @article{yang_kneller_2018, title={Neutrino flavour evolution through fluctuating matter}, volume={45}, ISSN={["1361-6471"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85044239930&partnerID=MN8TOARS}, DOI={10.1088/1361-6471/aab0c4}, abstractNote={A neutrino propagating through fluctuating matter can experience large amplitude transitions between its states. Such transitions occur in supernovae and compact object mergers due to turbulent matter profiles and neutrino self-interactions. In this paper we study, both numerically and analytically, three-flavour neutrino transformation through fluctuating matter built from two and three Fourier modes. We find flavor transformation effects which cannot occur with just two flavours. For the case of two Fourier modes we observe the equivalent of "induced transparency" from quantum optics whereby transitions between a given pair of states are suppressed due to the presence of a resonant mode between another pair. When we add a third Fourier mode we find a new effect whereby the third mode can manipulate the transition probabilities of the two mode case so as to force complete transparency or, alternatively, restore "opacity" meaning the perturbative Hamiltonian regains its ability to induce neutrino flavour transitions. In both applications we find analytic solutions are able to match the amplitude and wavenumber of the numerical results to within a few percent. We then consider a case of turbulence and show how the theory can be used to understand the very different response of a neutrino to what appears to be two, almost identical, instances of turbulence.}, number={4}, journal={JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS}, author={Yang, Y. and Kneller, J. P.}, year={2018}, month={Apr} }
 @article{horiuchi_kneller_2018, title={What can be learned from a future supernova neutrino detection?}, volume={45}, url={http://dx.doi.org/10.1088/1361-6471/aaa90a}, DOI={10.1088/1361-6471/aaa90a}, abstractNote={This year marks the thirtieth anniversary of the only supernova from which we have detected neutrinos - SN 1987A. The twenty or so neutrinos that were detected were mined to great depth in order to determine the events that occurred in the explosion and to place limits upon all manner of neutrino properties. Since 1987 the scale and sensitivity of the detectors capable of identifying neutrinos from a Galactic supernova have grown considerably so that current generation detectors are capable of detecting of order ten thousand neutrinos for a supernova at the Galactic Center. Next generation detectors will increase that yield by another order of magnitude. Simultaneous with the growth of neutrino detection capability, our understanding of how massive stars explode and how the neutrino interacts with hot and dense matter has also increased by a tremendous degree. The neutrino signal will contain much information on all manner of physics of interest to a wide community. In this review we describe the expected features of the neutrino signal, the detectors which will detect it, and the signatures one might try to look for in order to get at these physics.}, number={4}, journal={Journal of Physics G: Nuclear and Particle Physics}, author={Horiuchi, S. and Kneller, J.P.}, year={2018}, month={Apr} }
 @misc{horiuchi_kneller_2018, title={What can be learned from a future supernova neutrino detection?}, volume={45}, number={4}, journal={Journal of Physics. G, Nuclear and Particle Physics}, author={Horiuchi, S. and Kneller, J. P.}, year={2018} }
 @article{yang_kneller_2017, title={GR effects in supernova neutrino flavor transformations}, volume={96}, ISSN={["2470-0029"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85027052291&partnerID=MN8TOARS}, DOI={10.1103/physrevd.96.023009}, abstractNote={The strong gravitational field around a proto-neutron star can modify the neutrino flavor transformations that occur above the neutrinosphere via three General Relativistic (GR) effects: time dilation, energy redshift, and trajectory bending. Depending on the compactness of the central object, the neutrino self-interaction potential is up to three times as large as that without GR principally due to trajectory bending which increases the intersection angles between different neutrino trajectories, and time dilation which changes the fluxes. We determine whether GR effects are important for flavor transformation during the different epochs of a supernova by using multi-angle flavor transformation calculations and consider a density profile and neutrino spectra representative of both the accretion and cooling phases. We find the GR effects are smaller during the accretion phase due to low compactness of the proto-neutron star and merely delay the decoherence; the neutrino bipolar oscillations during the cooling phase are also delayed due to the GR effects but the delay may be more important because the delay occurs at radii where it might alter the nucleosynthesis in the neutrino driven wind.}, number={2}, journal={PHYSICAL REVIEW D}, author={Yang, Yue and Kneller, James P.}, year={2017}, month={Jul} }
 @article{wright_kneller_2017, title={Neutrino Intensity Interferometry: Measuring Protoneutron Star Radii During Core-Collapse Supernovae}, volume={119}, ISSN={["1079-7114"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85026815010&partnerID=MN8TOARS}, DOI={10.1103/physrevlett.119.051101}, abstractNote={Intensity interferometry is a technique that has been used to measure the size of sources ranging from the quark-gluon plasma formed in heavy ion collisions to the radii of stars. We investigate using the same technique to measure protoneutron star (PNS) radii with the neutrino signal received from a core-collapse supernovae. Using a full wave-packet analysis, including the neutrino mass for the first time, we derive criteria where the effect can be expected to provide the desired signal, and find that neutrinos from the next Galactic supernova should contain extractable PNS radius information.}, number={5}, journal={PHYSICAL REVIEW LETTERS}, author={Wright, Warren P. and Kneller, James P.}, year={2017}, month={Aug} }
 @article{wright_gilmer_frohlich_kneller_2017, title={Neutrino signal from pair-instability supernovae}, volume={96}, ISSN={["2470-0029"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85037131414&partnerID=MN8TOARS}, DOI={10.1103/physrevd.96.103008}, abstractNote={A very massive star with a carbon-oxygen core in the range of $64$ M$_{\odot}<M_{\mathrm{CO}}<133$ M$_{\odot}$ is expected to undergo a very different kind of explosion known as a pair instability supernova. Pair instability supernovae are candidates for superluminous supernovae due to the prodigious amounts of radioactive elements they create. While the basic mechanism for the explosion is understood, how a star reaches a state is not, thus observations of a nearby pair-instability supernova would allow us to test current models of stellar evolution at the extreme of stellar masses. Much will be sought within the electromagnetic radiation we detect from such a supernova but we should not forget that the neutrinos from a pair-instability supernova contain unique signatures of the event that unambiguously identify this type of explosion. We calculate the expected neutrino flux at Earth from two, one-dimensional pair-instability supernova simulations which bracket the mass range of stars which explode by this mechanism taking into account the full time and energy dependence of the neutrino emission and the flavor evolution through the outer layers of the star. We calculate the neutrino signals in five different detectors chosen to represent present or near future designs. We find the more massive progenitors explode as pair-instability supernova which can easily be detected in multiple different neutrino detectors at the `standard' supernova distance of $10\;{\rm kpc}$ producing several events in DUNE, JUNE and SuperKamiokande, while the lightest progenitors only produce a handful of events (if any) in the same detectors. The proposed HyperKamiokande detector would detect neutrinos from a large pair-instability supernova as far as $\sim 50\;{\rm kpc}$ allowing it to reach the Megallanic Clouds and the several very high mass stars known to exist there.}, number={10}, journal={PHYSICAL REVIEW D}, author={Wright, Warren P. and Gilmer, Matthew S. and Frohlich, Carla and Kneller, James P.}, year={2017}, month={Nov} }
 @article{wright_kneller_ohlmann_roepke_scholberg_seitenzahl_2017, title={Neutrinos from type Ia supernovae: The gravitationally confined detonation scenario}, volume={95}, ISSN={["2470-0029"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85021867099&partnerID=MN8TOARS}, DOI={10.1103/physrevd.95.043006}, abstractNote={Despite their use as cosmological distance indicators and their importance in the chemical evolution of galaxies, the unequivocal identification of the progenitor systems and explosion mechanism of normal type Ia supernova (SN Ia) remains elusive. The leading hypothesis is that such a supernova is a thermonuclear explosion of a carbon-oxygen white dwarf, but the exact explosion mechanism is still a matter of debate. Observation of a galactic SN Ia would be of immense value in answering the many open questions related to these events. One potentially useful source of information about the explosion mechanism and progenitor is the neutrino signal. 
In this paper we compute the expected neutrino signal from a gravitationally confined detonation (GCD) explosion scenario for a SN~Ia and show how the flux at Earth contains features in time and energy unique to this scenario. We then calculate the expected event rates in the Super-K, Hyper-K, JUNO, DUNE, and IceCube detectors and find both Hyper-K and IceCube would see a few events for a GCD supernova at 1 kpc or closer, while Super-K, JUNO, and DUNE would see a events if the supernova were closer than ${\sim}0.3$ kpc. The distance and detector criteria needed to resolve the time and spectral features arising from the explosion mechanism, neutrino production, and neutrino oscillation processes are also discussed. 
The neutrino signal from the GCD is then compared with the signal from a deflagration-to-detonation transition (DDT) explosion model computed previously. We find the overall event rate is the most discriminating feature between the two scenarios followed by the event rate time structure. Using the event rate in the Hyper-K detector alone, the DDT can be distinguished from the GCD at 2$\sigma$ if the distance to the supernova is less than $2.3\;{\rm kpc}$ for a normal mass ordering and $3.6\;{\rm kpc}$ for an inverted ordering.}, number={4}, journal={PHYSICAL REVIEW D}, author={Wright, Warren P. and Kneller, James P. and Ohlmann, Sebastian T. and Roepke, Friedrich K. and Scholberg, Kate and Seitenzahl, Ivo R.}, year={2017}, month={Feb} }
 @article{kneller_de los reyes_2017, title={The effect of core-collapse supernova accretion phase turbulence on neutrino flavor evolution}, volume={44}, url={http://dx.doi.org/10.1088/1361-6471/aa7bc8}, DOI={10.1088/1361-6471/aa7bc8}, abstractNote={During the accretion phase of a core-collapse supernovae, large amplitude turbulence is generated by the combination of the standing accretion shock instability and convection driven by neutrino heating. The turbulence directly affects the dynamics of the explosion, but there is also the possibility of an additional, indirect, feedback mechanism due to the effect turbulence can have upon neutrino flavor evolution and thus the neutrino heating. In this paper we consider the effect of turbulence during the accretion phase upon neutrino evolution, both numerically and analytically. Adopting representative supernova profiles taken from the accretion phase of a supernova simulation, we find the numerical calculations exhibit no effect from turbulence. We explain this absence using two analytic descriptions: the Stimulated Transition model and the Distorted Phase Effect model. In the Stimulated Transition model turbulence effects depend upon six different lengthscales, and three criteria must be satisfied between them if one is to observe a change in the flavor evolution due to Stimulated Transition. We further demonstrate that the Distorted Phase Effect depends upon the presence of multiple semi-adiabatic MSW resonances or discontinuities that also can be expressed as a relationship between three of the same lengthscales. When we examine the supernova profiles used in the numerical calculations we find the three Stimulated Transition criteria cannot be satisfied, independent of the form of the turbulence power spectrum, and that the same supernova profiles lack the multiple semi-adiabatic MSW resonances or discontinuities necessary to produce a Distorted Phase Effect. Thus we conclude that even though large amplitude turbulence is present in supernova during the accretion phase, it has no effect upon neutrino flavor evolution.}, number={8}, journal={Journal of Physics G: Nuclear and Particle Physics}, author={Kneller, J.P. and De Los Reyes, M.}, year={2017}, month={Aug} }
 @article{kneller_reyes_2017, title={The effect of core-collapse supernova accretion phase turbulence on neutrino flavor evolution}, volume={44}, number={8}, journal={Journal of Physics. G, Nuclear and Particle Physics}, author={Kneller, J. P. and Reyes, M.}, year={2017} }
 @article{wright_nagaraj_kneller_scholberg_seitenzahl_2016, title={Neutrinos from type Ia supernovae: The deflagration-to-detonation transition scenario}, volume={94}, ISSN={["2470-0029"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84979671235&partnerID=MN8TOARS}, DOI={10.1103/physrevd.94.025026}, abstractNote={It has long been recognized that the neutrinos detected from the next core-collapse supernova in the Galaxy have the potential to reveal important information about the dynamics of the explosion and the nucleosynthesis conditions as well as allowing us to probe the properties of the neutrino itself. The neutrinos emitted from thermonuclear—type Ia—supernovae also possess the same potential, although these supernovae are dimmer neutrino sources. For the first time, we calculate the time, energy, line of sight, and neutrino-flavor-dependent features of the neutrino signal expected from a three-dimensional delayed-detonation explosion simulation, where a deflagration-to-detonation transition triggers the complete disruption of a near-Chandrasekhar mass carbon-oxygen white dwarf. We also calculate the neutrino flavor evolution along eight lines of sight through the simulation as a function of time and energy using an exact three-flavor transformation code. We identify a characteristic spectral peak at ˜10 MeV as a signature of electron captures on copper. This peak is a potentially distinguishing feature of explosion models since it reflects the nucleosynthesis conditions early in the explosion. We simulate the event rates in the Super-K, Hyper-K, JUNO, and DUNE neutrino detectors with the SNOwGLoBES event rate calculation software and also compute the IceCube signal. Hyper-K willmore » be able to detect neutrinos from our model out to a distance of ˜10 kpc. Here, at 1 kpc, JUNO, Super-K, and DUNE would register a few events while IceCube and Hyper-K would register several tens of events.« less}, number={2}, journal={PHYSICAL REVIEW D}, author={Wright, Warren P. and Nagaraj, Gautam and Kneller, James P. and Scholberg, Kate and Seitenzahl, Ivo R.}, year={2016}, month={Jul} }
 @article{stapleford_vaananen_kneller_mclaughlin_shapiro_2016, title={Nonstandard neutrino interactions in supernovae}, volume={94}, ISSN={["2470-0029"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85002112694&partnerID=MN8TOARS}, DOI={10.1103/physrevd.94.093007}, abstractNote={Nonstandard interactions (NSI) of neutrinos with matter can significantly alter neutrino flavor evolution in supernovae with the potential to impact explosion dynamics, nucleosynthesis, and the neutrinos signal. In this paper, we explore, both numerically and analytically, the landscape of neutrino flavor transformation effects in supernovae due to NSI and find a new, heretofore unseen transformation processes can occur. These new transformations can take place with NSI strengths well below current experimental limits. Within a broad swath of NSI parameter space, we observe symmetric and standard matter-neutrino resonances for supernovae neutrinos, a transformation effect previously only seen in compact object merger scenarios; in another region of the parameter space we find the NSI can induce neutrino collective effects in scenarios where none would appear with only the standard case of neutrino oscillation physics; and in a third region the NSI can lead to the disappearance of the high density Mikheyev-Smirnov-Wolfenstein resonance. Using a variety of analytical tools, we are able to describe quantitatively the numerical results allowing us to partition the NSI parameter according to the transformation processes observed. Our results indicate nonstandard interactions of supernova neutrinos provide a sensitive probe of beyond the Standard Model physics complementary to present and future terrestrial experiments.}, number={9}, journal={PHYSICAL REVIEW D}, author={Stapleford, Charles J. and Vaananen, Daavid J. and Kneller, James P. and McLaughlin, Gail C. and Shapiro, Brandon T.}, year={2016}, month={Nov} }
 @article{supernova physics at dune_2016, year={2016}, month={Aug} }
 @article{malkus_kneller_mclaughlin_surman_2015, title={Neutrino Oscillation Above a Black Hole Accretion Disk}, volume={1663}, ISSN={["0094-243X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85006201488&partnerID=MN8TOARS}, DOI={10.1063/1.4919479}, abstractNote={We examine neutrino oscillations in the context of an accretion disk surrounding a black hole. Because accretion disks produce large quantities of neutrinos, they may be home to interesting neutrino oscillation as well. We model accretion disks associated with stellar collapse for the sake of understanding neutrino oscillations. We find that the neutrino oscillations include phenomena seen in the protoneutron star setting as well as phenomena not seen elsewhere.}, journal={NUINT12: 8TH INTERNATIONAL WORKSHOP ON NEUTRINO-NUCLEUS INTERACTIONS IN THE FEW-GEV REGION}, author={Malkus, A. and Kneller, J. P. and McLaughlin, G. C. and Surman, R.}, year={2015} }
 @article{lund_kneller_2015, title={Neutrino flavor evolution in turbulent supernova matter}, volume={61}, ISSN={["1875-3892"]}, url={http://dx.doi.org/10.1016/j.phpro.2014.12.090}, DOI={10.1016/j.phpro.2014.12.090}, abstractNote={In order to decode the neutrino burst signal from a Galactic core-collapse supernova and reveal the complicated inner workings of the explosion, we need a thorough understanding of the neutrino flavor evolution from the proto-neutron-star outwards. The flavor content of the signal evolves due to both neutrino collective effects and matter effects which can lead to a highly interesting interplay and distinctive spectral features. In this paper we investigate the supernova neutrino flavor evolution by including collective flavor effects, the evolution of the Mikheyev, Smirnov & Wolfenstein (MSW) matter conversions due to the shock wave passing through the star, and the impact of turbulence. The density profiles utilized in our calculations represent a 10.8 MG progenitor and comes from a 1D numerical simulation by Fischer et al. [1]. We find that small amplitude turbulence, up to 10% of the average potential, leads to a minimal modification of the signal, and the emerging neutrino spectra retain both collective and MSW features. However, when larger amounts of turbulence are added, 30% and 50%, the features of collective and shock wave effects in the high density resonance channel are almost completely obscured at late times. At the same time we find the other mixing channels – the low density resonance channel and the non-resonant channels – begin to develop turbulence signatures. Large amplitude turbulent motions in the outer layers of massive, iron core-collapse supernovae may obscure the most obvious fingerprints of collective and shock wave effects in the neutrino signal but cannot remove them completely, and additionally bring about new features in the signal. We illustrate how the progression of the shock wave is reflected in the changing survival probabilities over time, and we show preliminary results on how some of these collective and shock wave induced signatures appear in a detector signal.}, journal={13TH INTERNATIONAL CONFERENCE ON TOPICS IN ASTROPARTICLE AND UNDERGROUND PHYSICS, TAUP 2013}, author={Lund, Tina and Kneller, James P.}, year={2015}, pages={729–736} }
 @article{kneller_kabadi_2015, title={Sensitivity of neutrinos to the supernova turbulence power spectrum: Point source statistics}, volume={92}, ISSN={["1550-2368"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84939139530&partnerID=MN8TOARS}, DOI={10.1103/physrevd.92.013009}, abstractNote={The neutrinos emitted from the proto-neutron star created in a core-collapse supernova must run through a significant amount of turbulence before exiting the star. Turbulence can modify the flavor evolution of the neutrinos imprinting itself upon the signal detected here at Earth. The turbulence effect upon individual neutrinos, and the correlation between pairs of neutrinos, might exhibit sensitivity to the power spectrum of the turbulence, and recent analysis of the turbulence in a two-dimensional hydrodynamical simulation of a core-collapse supernova indicates the power spectrum may not be the Kolmogorov 5 /3 inverse power law as has been previously assumed. In this paper we study the effect of non-Kolmogorov turbulence power spectra upon neutrinos from a point source as a function of neutrino energy and turbulence amplitude at a fixed postbounce epoch. We find the two effects of turbulence upon the neutrinos—the distorted phase effect and the stimulated transitions—both possess strong and weak limits in which dependence upon the power spectrum is absent or evident, respectively. Furthermore, since neutrinos of a given energy will exhibit these two effects at different epochs of the supernova each with evolving strength, we find there is sensitivity to the power spectrum present in the neutrinomore » burst signal from a Galactic supernova.« less}, number={1}, journal={PHYSICAL REVIEW D}, author={Kneller, James P. and Kabadi, Neel V.}, year={2015}, month={Jul} }
 @article{patton_kneller_mclaughlin_2015, title={Stimulated neutrino transformation through turbulence on a changing density profile and application to supernovae}, volume={91}, ISSN={["1550-2368"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84937147972&partnerID=MN8TOARS}, DOI={10.1103/physrevd.91.025001}, abstractNote={We apply the model of stimulated neutrino transitions to neutrinos travelling through turbulence on a non constant density profile. We describe a method to predict the location of large amplitude transitions and demonstrate the effectiveness of this method by comparing to numerical calculations using a model supernova (SN) profile. The important wavelength scales of turbulence, both those that stimulate neutrino transformations and those that suppress them, are presented and discussed. We then examine the effects of changing the parameters of the turbulent spectrum, specifically the root-mean-square amplitude and cutoff wavelength, and show how the stimulated transitions model offers an explanation for the increase in both the amplitude and number of transitions with large amplitude turbulence, as well as a suppression or absence of transitions for long cutoff wavelengths. The method can also be used to predict the location of transitions between anti-neutrino states which, in the normal hierarchy we are using, will not undergo Mikheev-Smirnov-Wolfenstein transitions. Lastly, the stimulated neutrino transitions method is applied to a turbulent 2D supernova simulation and explains the minimal observed effect on neutrino oscillations in the simulation as being due to excessive long wavelength modes suppressing transitions and the absence of modes that fulfill themore » parametric resonance condition.« less}, number={2}, journal={PHYSICAL REVIEW D}, author={Patton, Kelly M. and Kneller, James P. and McLaughlin, Gail C.}, year={2015}, month={Jan} }
 @article{the physics of supernova neutrino oscillations_2015, year={2015}, month={Jul} }
 @inproceedings{lund_kneller_2014, title={Flavor evolution of supernova neutrinos in turbulent matter}, volume={1604}, url={http://dx.doi.org/10.1063/1.4883435}, DOI={10.1063/1.4883435}, abstractNote={The neutrino signal from the next galactic supernova carries with it an enormous amount of information on the explosion mechanism of a core-collapse supernova, as well as on the stellar progenitor and on the neutrinos themselves. In order to extract this information we need to know how the neutrino flavor evolves over time due to the interplay of neutrino self-interactions and matter effects. Additional turbulence in the supernova matter may impart its own signatures on the neutrino spectrum, and could partly obscure the imprints of collective and matter effects. We investigate the neutrino flavor evolution due to neutrino self-interactions, matter effects due to the shock wave propagation, and turbulence in three progenitors with masses of 8.8 M⊙, 10.8 M⊙ and 18.0 M⊙. In the lightest progenitor we find that the impact of moderate turbulence of the order 10% is limited and occurs only briefly early on. This makes the signatures of collective and matter interactions relatively straightforward to interpret....}, publisher={AIP Publishing LLC}, author={Lund, Tina and Kneller, James P.}, year={2014}, pages={225–232} }
 @article{patton_kneller_mclaughlin_2014, title={Stimulated neutrino transformation through turbulence}, volume={89}, ISSN={["1550-2368"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84899723375&partnerID=MN8TOARS}, DOI={10.1103/physrevd.89.073022}, abstractNote={We derive an analytical solution for the flavor evolution of a neutrino through a turbulent density profile which is found to accurately predict the amplitude and transition wavelength of numerical solutions on a case-by-case basis. The evolution is seen to strongly depend upon those Fourier modes in the turbulence which are approximately the same as the splitting between neutrino eigenvalues. Transitions are strongly enhanced by those Fourier modes in the turbulence which are approximately the same as the splitting between neutrino eigenvalues. Lastly, we also find a suppression of transitions due to the long wavelength modes when the ratio of their amplitude and the wavenumber is of order, or greater than, the first root of the Bessel function J0.}, number={7}, journal={PHYSICAL REVIEW D}, author={Patton, Kelly M. and Kneller, James P. and McLaughlin, Gail C.}, year={2014}, month={Apr} }
 @article{kneller_mclaughlin_patton_2014, title={Turbulence and its effects upon neutrinos}, volume={1604}, ISSN={["0094-243X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84903938255&partnerID=MN8TOARS}, DOI={10.1063/1.4883432}, abstractNote={As a neutrino passes through turbulent matter, large amplitude transitions between its eigenstates can occur. These transitions can be modeled as like those of an irradiated polarized atom and we investigate this connection both analytically and numerically. We find a simple theory that makes use of the Rotating Wave Approximation can make predictions for the amplitudes and wavelengths of the transitions that agree very well with those from the numerical solutions.}, journal={WORKSHOP ON DARK MATTER, NEUTRINO PHYSICS AND ASTROPHYSICS CETUP 2013: VIITH INTERNATIONAL CONFERENCE ON INTERCONNECTIONS BETWEEN PARTICLE PHYSICS AND COSMOLOGY PPC 2013}, author={Kneller, J. P. and McLaughlin, G. C. and Patton, K. M.}, year={2014}, pages={204–209} }
 @article{lund_kneller_2013, title={Combining collective, MSW, and turbulence effects in supernova neutrino flavor evolution}, volume={88}, ISSN={["1550-2368"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84881268179&partnerID=MN8TOARS}, DOI={10.1103/physrevd.88.023008}, abstractNote={In order to decode the neutrino burst signal from a Galactic core-collapse supernova and reveal the complicated inner workings of the explosion we need a thorough understanding of the neutrino flavor evolution from the proto-neutron star outwards. The flavor content of the signal evolves due to both neutrino collective effects and matter effects which can lead to a highly interesting interplay and distinctive spectral features. In this paper we investigate the supernova neutrino flavor evolution in three different progenitors and include collective flavor effects, the evolution of the Mikheyev, Smirnov & Wolfenstein conversion due to the shock wave passage through the star, and the impact of turbulence. In the Oxygen-Neon-Magnesium supernova we find that the impact of turbulence is both brief and slight during a window of 1-2 seconds post bounce. Thus the spectral features of collective and shock effects in the neutrino signals from ONeMg supernovae may be almost turbulence free making them the easiest to interpret. For the more massive progenitors we again find that small amplitude turbulence, up to 10%, leads to a minimal modification of the signal, and the emerging neutrino spectra retain both collective and MSW features. However, when larger amounts of turbulence is added,more » 30% and 50%, the features of collective and shock wave effects in the high density resonance channel are almost completely obscured at late times. Yet at the same time we find the other mixing channels - the low density resonance channel and the non-resonant channels - begin to develop turbulence signatures. Large amplitude turbulent motions in the outer layers of more massive, iron core-collapse supernovae may obscure the most obvious fingerprints of collective and shock wave effects in the neutrino signal but cannot remove them completely, and additionally bring about new features in the signal.« less}, number={2}, journal={PHYSICAL REVIEW D}, author={Lund, Tina and Kneller, James P.}, year={2013}, month={Jul} }
 @article{kneller_mauney_2013, title={Consequences of large theta(13) for the turbulence signatures in supernova neutrinos}, volume={88}, ISSN={["1550-2368"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84881277450&partnerID=MN8TOARS}, DOI={10.1103/physrevd.88.025004}, abstractNote={Here, the transition probabilities for a single neutrino emitted from a point proto-neutron source after passage through a turbulent supernova density profile have been found to be random variates drawn from parent distributions whose properties depend upon the stage of the explosion, the neutrino energy and mixing parameters, the observed channel, and the properties of the turbulence such as the amplitude C*. In this paper we examine the consequences of the recently measured mixing angle θ13 upon the neutrino flavor transformation in supernova when passing through turbulence, in order to provide some clarity as to what one should expect in the way of turbulence effects in the next supernova neutrino burst signal. We find that the measurements of a relatively large value of θ13 means the neutrinos are relatively immune to small, C*≲1%, amplitude turbulence but as C* increases the turbulence effects grow rapidly and spread to all mixing channels. For C*≳10% the turbulence effects in the high density resonance mixing channels are independent of θ13 but nonresonant mixing channels are more sensitive to turbulence when θ13 is large.}, number={2}, journal={PHYSICAL REVIEW D}, author={Kneller, James P. and Mauney, Alex W.}, year={2013}, month={Jul} }
 @article{kneller_mauney_2013, title={Does the finite size of the proto-neutron star preclude supernova neutrino flavor scintillation due to turbulence?}, volume={88}, ISSN={["1550-2368"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84884835438&partnerID=MN8TOARS}, DOI={10.1103/physrevd.88.045020}, abstractNote={Here, the transition probabilities describing the evolution of a neutrino with a given energy along some ray through a turbulent supernova profile are random variates unique to each ray. If the proto-neutron-star source of the neutrinos were a point, then one might expect the evolution of the turbulence would cause the flavor composition of the neutrinos to vary in time i.e. the flavor would scintillate. But in reality the proto-neutron star is not a point source—it has a size of order ˜10km, so the neutrinos emitted from different points at the source will each have seen different turbulence. The finite source size will reduce the correlation of the flavor transition probabilities along different trajectories and reduce the magnitude of the flavor scintillation. To determine whether the finite size of the proto-neutron star will preclude flavor scintillation, we calculate the correlation of the neutrino flavor transition probabilities through turbulent supernova profiles as a function of the separation δx between the emission points. The correlation will depend upon the power spectrum used for the turbulence, and we consider two cases: when the power spectrum is isotropic, and the more realistic case of a power spectrum which is anisotropic on large scales andmore » isotropic on small. Although it is dependent on a number of uncalibrated parameters, we show the supernova neutrino source is not of sufficient size to significantly blur flavor scintillation in all mixing channels when using an isotropic spectrum, and this same result holds when using an anisotropic spectrum, except when we greatly reduce the similarity of the turbulence along parallel trajectories separated by ˜10km or less.« less}, number={4}, journal={PHYSICAL REVIEW D}, author={Kneller, James P. and Mauney, Alex W.}, year={2013}, month={Aug} }
 @article{kneller_mclaughlin_patton_2013, title={Stimulated neutrino transformation in supernovae}, volume={1560}, ISSN={["0094-243X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84890049775&partnerID=MN8TOARS}, DOI={10.1063/1.4826746}, abstractNote={Large amplitude oscillations between neutrino states can be stimulated by sinusoidal external potentials with frequencies that are equal to the energy level splitting of the states or a fraction thereof: a phenomenon known as parametric resonance. Simple expressions for the amplitude and wavelength of the neutrino transitions both on and off resonance can be derived that reproduce the numerical results well. When applied to the supernova environment one finds that it is possible to predict where stimulated transitions occur when a sinusoidal perturbation is superposed upon an underlying profile indicating that stimulated transitions may be a useful way of understanding the effect of fluctuating density profiles such as turbulence.}, journal={11TH CONFERENCE ON THE INTERSECTIONS OF PARTICLE AND NUCLEAR PHYSICS (CIPANP 2012)}, author={Kneller, James P. and McLaughlin, Gail C. and Patton, Kelly M.}, year={2013}, pages={176–178} }
 @article{kneller_mclaughlin_patton_2013, title={Stimulated neutrino transformation with sinusoidal density profiles}, volume={40}, ISSN={["0954-3899"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84876921182&partnerID=MN8TOARS}, DOI={10.1088/0954-3899/40/5/055002}, abstractNote={Large amplitude oscillations between the states of a quantum system can be stimulated by sinusoidal external potentials with frequencies that are similar to the energy level splitting of the states or a fraction thereof. Situations where the applied frequency is equal to an integer fraction of the energy level splittings are known as parametric resonances. We investigate this effect for neutrinos both analytically and numerically for the case of arbitrary numbers of neutrino flavors. We look for environments where the effect may be observed and find that supernovae are the one realistic possibility due to the necessity of both large densities and large amplitude fluctuations. In conclusion, the comparison of numerical and analytical results of neutrino propagation through a model supernova reveals that it is possible to predict the locations and strengths of the stimulated transitions that occur.}, number={5}, journal={JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS}, author={Kneller, J. P. and McLaughlin, G. C. and Patton, K. M.}, year={2013}, month={May} }
 @inproceedings{lund_kneller_2013, title={v propagation in turbulent supernova matter}, volume={1560}, booktitle={11th conference on the intersections of particle and nuclear physics (cipanp 2012)}, author={Lund, T. and Kneller, J. P.}, year={2013}, pages={333–335} }
 @article{malkus_kneller_mclaughlin_surman_2013, title={vs and nucleosynthesis from accretion disks}, volume={1560}, ISSN={["0094-243X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84890021433&partnerID=MN8TOARS}, DOI={10.1063/1.4826787}, abstractNote={Black hole accretion disks may occur in certain core collapse supernovae or in mergers of compact objects. This environment produces a strong flux of electron neutrinos and electron antineutrinos. These neutrinos are instrumental in determining the types of elements produced in disk outflows. In this context, using the single angle approximation and a constant temperature disk, we report on calculations of neutrino flavor oscillations driven by neutrino self interactions. We comment on some impacts to element synthesis.}, journal={11TH CONFERENCE ON THE INTERSECTIONS OF PARTICLE AND NUCLEAR PHYSICS (CIPANP 2012)}, author={Malkus, A. and Kneller, J. P. and McLaughlin, G. C. and Surman, R.}, year={2013}, pages={336–340} }
 @inproceedings{lund_kneller_2013, title={ν propagation in turbulent supernova matter}, volume={1560}, url={http://dx.doi.org/10.1063/1.4826786}, DOI={10.1063/1.4826786}, abstractNote={The flavor evolution of neutrinos propagating through a turbulent medium is a highly interesting and complicated problem. Depending upon the hierarchy and the properties of the turbulence, the neutrino spectral signatures of collective effects and/or shock waves in the supernova may be smothered to the point where they are unobservable in the "golden" channels (νe → μ transitions) of the next Galactic Supernova Neutrino Burst. Additionally, a more comprehensive understanding of the neutrino flavor evolution in supernova matter is necessary if we wish to use neutrinos to learn about the explosion mechanism. We investigate the effects of neutrino self-interactions, MSW conversions as well as the impact of turbulence on the neutrino flavor evolution along single radial directions in turbulent dense matter, paying special attention to the combined impact of these three effects. We find that adding up to 10% turbulence leads to only minor differences in the emerging neutrino spectra, while overall features of ...}, publisher={AIP}, author={Lund, Tina and Kneller, James P.}, year={2013}, pages={333–335} }
 @article{fundamental physics at the intensity frontier_2012, year={2012}, month={May} }
 @article{malkus_kneller_mclaughlin_surman_2012, title={Neutrino oscillations above black hole accretion disks: Disks with electron-flavor emission}, volume={86}, ISSN={["1550-2368"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84867260598&partnerID=MN8TOARS}, DOI={10.1103/physrevd.86.085015}, abstractNote={Department of Physics and Astronomy, Union College, Schenectady, NY 12308 USA(Dated: December 22, 2013)Black hole accretion disks can form through the collapse of rotating massive stars. These disksproduce large numbers of neutrinos and antineutrinos of electron flavor that can influence energeticsand nucleosynthesis. Neutrinos are produced in sufficient numbers that, after they are emitted, theycan undergo flavor transformation facilitated by the neutrino self interaction. We show that someof the neutrino flavor transformation phenomenology for accretion disks is similar to that of thesupernova case, but also, we find the disk geometry lends itself to different transformation behaviors.These transformations strongly influence the nucleosynthetic outcome of disk winds.}, number={8}, journal={PHYSICAL REVIEW D}, publisher={American Physical Society (APS)}, author={Malkus, A. and Kneller, J. P. and McLaughlin, G. C. and Surman, R.}, year={2012}, month={Oct} }
 @article{galais_kneller_volpe_2012, title={The neutrino–neutrino interaction effects in supernovae: the point of view from the ‘matter’ basis}, volume={39}, url={http://dx.doi.org/10.1088/0954-3899/39/3/035201}, DOI={10.1088/0954-3899/39/3/035201}, abstractNote={We consider the Hamiltonian for neutrino oscillations in matter in the case of arbitrary potentials including off-diagonal complex terms. We derive the expressions for the corresponding Hamiltonian in the basis of the instantaneous eigenstates in matter, in terms of quantities one can derive from the flavor-basis Hamiltonian and its derivative, for an arbitrary number of neutrino flavors. We make our expressions explicit for the two-neutrino flavor case and apply our results to the neutrino propagation in core-collapse supernovae where the Hamiltonian includes both coupling to matter and to neutrinos. We show that the neutrino flavor evolution depends on the mixing matrix derivatives involving not only the derivative of the matter mixing angles but also of the phases. In particular, we point out the important role of the phase derivatives, that appear due to the neutrino?neutrino interaction, and show how it can cause an oscillating degeneracy between the diagonal elements of the Hamiltonian in the basis of the eigenstates in matter. Our results also reveal that the end of the synchronization regime is due to a rapid increase of the phase derivative and identify the condition to be fulfilled for the onset of bipolar oscillations involving both the off-diagonal neutrino?neutrino interaction contributions and the vacuum terms.}, number={3}, journal={Journal of Physics G: Nuclear and Particle Physics}, author={Galais, S. and Kneller, J. and Volpe, C.}, year={2012}, month={Mar} }
 @article{the 2010 interim report of the long-baseline neutrino experiment collaboration physics working groups_2011, year={2011}, month={Oct} }
 @article{kneller_2011, title={The effect of turbulence upon supernova neutrinos}, volume={217}, url={http://dx.doi.org/10.1016/j.nuclphysbps.2011.04.080}, DOI={10.1016/j.nuclphysbps.2011.04.080}, abstractNote={Multidimensional supernova simulations indicate the presence of large scale, low multipole, asphericity generated deep within the star during the accretion phase. When density fluctuations are present in the high (H) density resonance region the neutrino flavour evolution is modified compared to the case sans turbulence. We investigate the effects of the turbulent density profiles upon the neutrinos as a function of the fluctuation amplitude and the mixing angle θ13 and find that: turbulence effects in the H resonance channel are inevitable if θ13 is large, and large amplitude fluctuations extend the sensitivity to θ13, break high-low (HL) density resonance factorization and generate non-trivial survival probabilities in the non-resonant channels.}, number={1}, journal={Nuclear Physics B - Proceedings Supplements}, author={Kneller, J.P.}, year={2011}, month={Aug}, pages={118–120} }
 @inproceedings{kneller_2011, title={The effect of turbulence upon supernova neutrinos}, volume={217}, booktitle={Nuclear Physics. B, Proceedings, Supplements}, author={Kneller, J. P.}, year={2011}, pages={118–120} }
 @inproceedings{kneller_2011, title={Turbulence and supernova neutrinos}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84883507340&partnerID=MN8TOARS}, DOI={10.3204/DESY-PROC-2011-03/kneller}, booktitle={Proceedings of the Hamburg Neutrinos from Supernova Explosions, HAvSE 2011}, author={Kneller, J.P.}, year={2011}, pages={84–89} }
 @article{galais_kneller_volpe_gava_2010, title={Shock waves in supernovae: New implications on the diffuse supernova neutrino background}, volume={81}, url={http://dx.doi.org/10.1103/physrevd.81.053002}, DOI={10.1103/physrevd.81.053002}, abstractNote={We investigate shock wave effects upon the diffuse supernova neutrino background using dynamic profiles taken from hydrodynamical simulations and calculating the neutrino evolution in three flavors with the S-matrix formalism. We show that the shock wave impact is significant and introduces modifications of the relic fluxes by about 20% and of the associated event rates at the level of 10%-20%. Such an effect is important since it is of the same order as the rate variation introduced when different oscillation scenarios (i.e., hierarchy or θ 13 ) are considered. In addition, due to the shock wave, the rates become less sensitive to collective effects, in the inverted hierarchy and when sin 2 2θ 13 is between the Chooz limit and 10 -5 . We propose a simplified model to account for shock wave effects in future predictions.}, number={5}, journal={Physical Review D}, author={Galais, S. and Kneller, J. and Volpe, C. and Gava, J.}, year={2010}, month={Mar} }
 @article{kneller_volpe_2010, title={Turbulence effects on supernova neutrinos}, volume={82}, url={http://dx.doi.org/10.1103/physrevd.82.123004}, DOI={10.1103/physrevd.82.123004}, abstractNote={Multidimensional core-collapse supernova simulations exhibit turbulence of large amplitude and over large scales. As neutrinos pass through the supernova mantle the turbulence is expected to modify their evolution compared to the case where the explosion is free of turbulence. In this paper we study this turbulence effect upon the neutrinos modeling the turbulence expected from multidimensional simulations by adding matter density fluctuations to density profiles taken from one-dimensional hydrodynamical simulations. We investigate the impact upon the supernova neutrino transition probabilities as a function of the neutrino mixing angle θ 13 and turbulence amplitude. In the high resonant channel and with large θ 13 values we find that turbulence is effectively two flavor for fluctuation amplitudes ≲ 1% and have identified a new effect due to the combination of turbulence and multiple high resonances that leads to a sensitivity to fluctuations amplitudes as small as ~0.001%. At small values of θ 13 , beyond the range achievable in Earth based experiments, we find that turbulence leads to new flavor transient effects in the channel where the Mikheev-Smirnov-Wolfenstein high resonance occurs. Finally, we investigate large amplitude fluctuations which lead to three-flavor effects due to broken high-low factorization and significant nonresonant transitions and identify two nonresonant turbulence effects, one depending on the θ 13 , and the other independent of this angle and due to the low Mikheev-Smimov-Wolfenstein resonance.}, number={12}, journal={Physical Review D}, author={Kneller, J. and Volpe, C.}, year={2010}, month={Dec} }
 @article{gava_kneller_volpe_mclaughlin_2009, title={Dynamical Collective Calculation of Supernova Neutrino Signals}, volume={103}, ISSN={["1079-7114"]}, url={http://dx.doi.org/10.1103/physrevlett.103.071101}, DOI={10.1103/physrevlett.103.071101}, abstractNote={We present the first calculations with three flavors of collective and shock wave effects for neutrino propagation in core-collapse supernovae using hydrodynamical density profiles and the S matrix formalism. We explore the interplay between the neutrino-neutrino interaction and the effects of multiple resonances upon the time signal of positrons in supernova observatories. A specific signature is found for the inverted hierarchy and a large third neutrino mixing angle and we predict, in this case, a dearth of lower energy positrons in Cherenkov detectors midway through the neutrino signal and the simultaneous revelation of valuable information about the original fluxes. We show that this feature is also observable with current generation neutrino detectors at the level of several sigmas.}, number={7}, journal={PHYSICAL REVIEW LETTERS}, author={Gava, Jerome and Kneller, James and Volpe, Cristina and McLaughlin, G. C.}, year={2009}, month={Aug} }
 @article{duan_kneller_2009, title={Neutrino flavour transformation in supernovae}, volume={36}, url={http://dx.doi.org/10.1088/0954-3899/36/11/113201}, DOI={10.1088/0954-3899/36/11/113201}, abstractNote={Rapid progress has been made during recent years in the understanding of the flavour oscillations that occur as neutrinos traverse through supernova. The previous paradigm has given way and it is now clear that the neutrino signals we shall receive from future Galactic supernovae will allow us both to peer inside these extraordinary cosmic events and to probe some of the fundamental properties of these elusive particles. In this review we aim to distill the progress that has been made focusing upon the effects of the dynamic density profile and the emergence of collective flavour oscillations due to neutrino self-interactions.}, number={11}, journal={Journal of Physics G: Nuclear and Particle Physics}, author={Duan, H. and Kneller, J.P.}, year={2009}, month={Nov} }
 @article{kneller_mclaughlin_2009, title={Three flavor neutrino oscillations in matter: Flavor diagonal potentials, the adiabatic basis, and the CP phase}, volume={80}, ISSN={["1550-2368"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-70349782067&partnerID=MN8TOARS}, DOI={10.1103/physrevd.80.053002}, abstractNote={We discuss the three neutrino flavor evolution problem with general, flavor-diagonal, matter potentials and a fully parametrized mixing matrix that includes $CP$ violation, and derive expressions for the eigenvalues, mixing angles, and phases. We demonstrate that, in the limit that the mu and tau potentials are equal, the eigenvalues and matter mixing angles ${\stackrel{\texttildelow{}}{\ensuremath{\theta}}}_{12}$ and ${\stackrel{\texttildelow{}}{\ensuremath{\theta}}}_{13}$ are independent of the $CP$ phase, although ${\stackrel{\texttildelow{}}{\ensuremath{\theta}}}_{23}$ does have $CP$ dependence. Since we are interested in developing a framework that can be used for $S$ matrix calculations of neutrino flavor transformation, it is useful to work in a basis that contains only off-diagonal entries in the Hamiltonian. We derive the ``nonadiabaticity'' parameters that appear in the Hamiltonian in this basis. We then introduce the neutrino $S$ matrix, derive its evolution equation and the integral solution. We find that this new Hamiltonian, and therefore the $S$ matrix, in the limit that the $\ensuremath{\mu}$ and $\ensuremath{\tau}$ neutrino potentials are the same, is independent of both ${\stackrel{\texttildelow{}}{\ensuremath{\theta}}}_{23}$ and the $CP$ violating phase. In this limit, any $CP$ violation in the flavor basis can only be introduced via the rotation matrices, and so effects which derive from the $CP$ phase are then straightforward to determine. We then show explicitly that the electron neutrino and electron antineutrino survival probability is independent of the $CP$ phase in this limit. Conversely, if the $CP$ phase is nonzero and mu and tau matter potentials are not equal, then the electron neutrino survival probability cannot be independent of the $CP$ phase.}, number={5}, journal={PHYSICAL REVIEW D}, author={Kneller, James P. and McLaughlin, Gail C.}, year={2009}, month={Sep} }
 @article{kneller_mclaughlin_brockman_2008, title={Oscillation effects and time variation of the supernova neutrino signal}, volume={77}, ISSN={["1550-2368"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-41049093044&partnerID=MN8TOARS}, DOI={10.1103/physrevd.77.045023}, abstractNote={The neutrinos detected from the next galactic core-collapse supernova will contain valuable information on the internal dynamics of the explosion. One mechanism leading to a temporal evolution of the neutrino signal is the variation of the induced neutrino flavor mixing driven by changes in the density profile. With one and two-dimensional hydrodynamical simulations we identify the behavior and properties of prominent features of the explosion. Using these results we demonstrate the time variation of the neutrino crossing probabilities due to changes in the Mikheyev-Smirnov-Wolfenstein (MSW) neutrino transformations as the star explodes by using the S-matrix--Monte Carlo--approach to neutrino propagation. After adopting spectra for the neutrinos emitted from the proto-neutron star we calculate for a galactic supernova the evolution of the positron spectra within a water Cerenkov detector and find that this signal allows us to probe of a number of explosion features.}, number={4}, journal={PHYSICAL REVIEW D}, author={Kneller, James P. and McLaughlin, Gail C. and Brockman, Justin}, year={2008}, month={Feb} }
 @article{kneller_mclaughlin_2006, title={Monte Carlo neutrino oscillations}, volume={73}, ISSN={["1550-2368"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33645470067&partnerID=MN8TOARS}, DOI={10.1103/physrevd.73.056003}, abstractNote={We demonstrate that the effects of matter upon neutrino propagation may be recast as the scattering of the initial neutrino wave function. Exchanging the differential, Schrodinger equation for an integral equation for the scattering matrix S permits a Monte Carlo method for the computation of S that removes many of the numerical difficulties associated with direct integration techniques.}, number={5}, journal={PHYSICAL REVIEW D}, author={Kneller, JP and McLaughlin, GC}, year={2006}, month={Mar} }
 @article{kneller_mclaughlin_surman_2006, title={Neutrino scattering, absorption and annihilation above the accretion discs of gamma ray bursts}, volume={32}, ISSN={["1361-6471"]}, url={http://dx.doi.org/10.1088/0954-3899/32/4/004}, DOI={10.1088/0954-3899/32/4/004}, abstractNote={The central engine that drives gamma ray burst (GRB) explosions may derive from the ability of electrons/positrons and nucleons to tap into the momentum and energy from the large neutrino luminosity emitted by an accretion disc surrounding a black hole. This transfer of momentum and energy occurs due to neutrino absorption, scattering and annihilation, and the non-spherical geometry of the source both increases the annihilation efficiency and, close to the black hole, directs the momentum transfer toward the disc axis. We focus on the micro-physical aspects of this system and present annihilation efficiencies and the momentum/energy transfers for a number of accretion disc models. Models in which the neutrinos and antineutrinos become trapped within the disc have noticeably different momentum and energy deposition structure compared to thin disc models that may lead to significant differences in the explosion dynamics. Using these results we make estimates for the critical densities of infalling material below which the transfer of neutrino momentum/energy will lead to an explosion.}, number={4}, journal={JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS}, author={Kneller, JP and McLaughlin, GC and Surman, RA}, year={2006}, month={Apr}, pages={443–462} }
 @article{kneller_2005, title={Measuring the amount of dark radiation with the CMB and BBN}, volume={138}, ISSN={["0920-5632"]}, url={http://dx.doi.org/10.1016/j.nuclphysbps.2004.11.017}, DOI={10.1016/j.nuclphysbps.2004.11.017}, abstractNote={The anisotropies in the cosmic microwave background (CMB) and big bang nucleosynthesis (BBN) are powerful probes of the energy density in relativistic particles. We show how the results from the Wilkinson Microwave Anisotropy Probe (WMAP), and new measurements of the primordial deuterium abundance, have improved the accuracy with which this component can be measured even in the case of a degeneracy in the electron neutrinos.}, number={Jan-05}, journal={NUCLEAR PHYSICS B-PROCEEDINGS SUPPLEMENTS}, author={Kneller, JP}, year={2005}, month={Jan}, pages={73–75} }
 @article{kneller_steigman_2004, title={BBN for pedestrians}, volume={6}, url={http://dx.doi.org/10.1088/1367-2630/6/1/117}, DOI={10.1088/1367-2630/6/1/117}, abstractNote={The simplest, ‘standard’ model of Big Bang nucleosynthesis (SBBN) assumes three light neutrinos (Nν = 3) and no significant electron neutrino asymmetry ( asymmetry parameter ξe ≡ μe/kT, where μe is the chemical potential of νe) leaving only one adjustable parameter: the baryon to photon ratio η ≡ nB/nγ. The primordial abundance of any one nuclide can, therefore, be used to measure η and the value derived from the observationally inferred primordial abundance of deuterium closely matches that from current non-BBN data, primarily from the WMAP survey. However, using this same estimate for η, there is a tension between the SBBN-predicted abundances of 4He and 7Li and their current, observationally inferred primordial abundances, suggesting that Nν may differ from the standard model value of three and/or that ξe may differ from zero (or, that systematic errors in the abundance determinations have been underestimated or overlooked). The differences are not large and the allowed ranges of the BBN parameters (η, Nν and ξe) permitted by the data are quite small. Within these ranges, the BBN-predicted abundances of D, 3He, 4He, and 7Li are very smooth, monotonic functions of η10, ΔNν ≡ Nν − 3 and ξe. As a result, it is possible to describe the dependence of these abundances (or powers of them) upon the three parameters by simple, linear fits which, over their ranges of applicability, are accurate to a few per cent or even better. The fits presented here have not been maximized for their accuracy but, rather, for their simplicity. To identify the ranges of applicability and relative accuracies, they are compared with detailed BBN calculations; their utility is illustrated with several examples. Given the tension within BBN, these fits should prove useful in facilitating studies of the viability of various options for non-standard physics and cosmology, prior to undertaking detailed BBN calculations.}, number={2004}, journal={New Journal of Physics}, author={Kneller, James and Steigman, G.}, year={2004}, month={Sep}, pages={1–22} }
 @article{kneller_steigman_2004, title={BBN for pedestrians}, volume={6}, number={2004}, journal={New Journal of Physics}, author={Kneller, J. P. and Steigman, G.}, year={2004} }
 @article{kneller_mclaughlin_2004, title={Effect of bound dineutrons upon big bang nucleosynthesis}, volume={70}, ISSN={["1550-2368"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-42749099171&partnerID=MN8TOARS}, DOI={10.1103/physrevd.70.043512}, abstractNote={We have examined the effects of a bound dineutron, n2, upon big bang nucleosynthesis (BBN) as a function of its binding energy B_n2. We find a weakly bound dineutron has little impact but as B_n2 increases its presence begins to alter the flow of free nucleons to helium-4. Due to this disruption, and in the absence of changes to other binding energies or fundamental constants, BBN sets a reliable upper limit of B_n2 <~ 2.5 MeV in order to maintain the agreement with the observations of the primordial helium-4 mass fraction and D/H abundance.}, number={4}, journal={PHYSICAL REVIEW D}, author={Kneller, JP and McLaughlin, GC}, year={2004}, month={Aug} }
 @article{kneller_steigman_2003, title={Big bang nucleosynthesis and CMB constraints on dark energy}, volume={67}, url={http://dx.doi.org/10.1103/physrevd.67.063501}, DOI={10.1103/physrevd.67.063501}, abstractNote={Current observational data favor cosmological models which differ from the standard model due to the presence of some form of dark energy and, perhaps, by additional contributions to the more familiar dark matter. Primordial nucleosynthesis provides a window on the very early evolution of the universe and constraints from Big Bang Nucleosynthesis (BBN) can bound the parameters of models for dark matter/energy at redshifts of order ten billion. The spectrum of temperature fluctuations imprinted on the Cosmic Microwave Background (CMB) radiation opens a completely different window on the universe at epochs from redshifts of order ten thousand to nearly the present. The CMB anisotropy spectrum provides constraints on new physics which are independent of, and complementary to those from BBN. Here we consider three classes of models for the dark matter/energy: extra particles which were relativistic during the early evolution of the universe (“ X ”); Quintessence models involving a minimally-coupled scalar field (“ Q ”); models with a non-minimally coupled scalar field which modify the strength of gravity during the early evolution of the universe (“ G ”). We constrain the parameters of these models using data from BBN and the CMB and identify the allowed regions in their parameter spaces consistent with the more demanding joint BBN and CMB constraints. For “ X ” and “ Q ” such consistency is relatively easy to find; it is more difficult for the “ G ” models with an inverse power law potential for the scalar field.}, number={6}, journal={Physical Review D}, author={Kneller, James and Steigman, G.}, year={2003}, month={Mar}, pages={063501–1} }
 @article{kneller_steigman_2003, title={Big bang nucleosynthesis and CMB constraints on dark energy}, volume={67}, number={6}, journal={Physical Review. D, Particles and Fields}, author={Kneller, J. P. and Steigman, G.}, year={2003}, pages={063501–1} }
 @article{kneller_mclaughlin_2003, title={Big bang nucleosynthesis and Lambda(QCD)}, volume={68}, ISSN={["2470-0029"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85038990077&partnerID=MN8TOARS}, DOI={10.1103/physrevd.68.103508}, abstractNote={Big Bang Nucleosynthesis (BBN) has increasingly become the tool of choice for investigating the permitted variation of fundamental constants during the earliest epochs of the Universe. Here we present a BBN calculation that has been modified to permit changes in the QCD scale, Λ QCD . The primary effects of changing the QCD scale upon BBN are through the deuteron binding energy, B D , and the neutron-proton mass difference, δm np , which both play crucial roles in determining the primordial abundances. In this paper, we show how a simplified BBN calculation allows us to restrict the nuclear data we need to just B D and δm np yet still gives useful results so that any variation in Λ QCD may be constrained via the corresponding shifts in B D and δm np by using the current estimates of the primordial deuterium abundance and helium mass fraction. The simplification predicts the helium-4 and deuterium abundances to within 1% and 50% respectively when compared with the results of a standard BBN code. But Λ QCD also affects much of remaining required nuclear input so this method introduces a systematic error into the calculation and we find a degeneracy between B D and δm np . We show how increased understanding of the relationship of the pion mass and/or B D to other nuclear parameters, such as the binding energy of tritium and the cross section of T + D → 4 He + n , would yield constraints upon any change in B D and δm np at the 10% level.}, number={10}, journal={PHYSICAL REVIEW D}, author={Kneller, JP and McLaughlin, GC}, year={2003}, month={Nov} }
 @article{barger_kneller_lee_marfatia_steigman_2003, title={Effective number of neutrinos and baryon asymmetry from BBN and WMAP}, volume={566}, url={http://dx.doi.org/10.1016/s0370-2693(03)00800-1}, DOI={10.1016/s0370-2693(03)00800-1}, abstractNote={We place constraints on the number of relativistic degrees of freedom and on the baryon asymmetry at the epoch of Big Bang Nucleosynthesis (BBN) and at recombination, using cosmic background radiation (CBR) data from the Wilkinson Microwave Anisotropy Probe (WMAP), complemented by the Hubble Space Telescope (HST) Key Project measurement of the Hubble constant, along with the latest compilation of deuterium abundances and Hii region measurements of the primordial helium abundance. The agreement between the derived values of these key cosmological and particle physics parameters at these widely separated (in time or redshift) epochs is remarkable. From the combination of CBR and BBN data, we find the 2σ ranges for the effective number of neutrinos Nν and for the baryon asymmetry (baryon to photon number ratio η) to be 1.7–3.0 and 5.53–6.76×10−10, respectively.}, number={1-2}, journal={Physics Letters B}, author={Barger, V. and Kneller, James and Lee, H.-S. and Marfatia, D. and Steigman, G.}, year={2003}, month={Jul}, pages={8–18} }
 @article{barger_kneller_lee_marfatia_steigman_2003, title={Effective number of neutrinos and baryon asymmetry from BBN and WMAP}, volume={566}, number={02-Jan}, journal={Physics Letters. B}, author={Barger, V. and Kneller, J. P. and Lee, H. S. and Marfatia, D. and Steigman, G.}, year={2003}, pages={18-} }
 @article{barger_kneller_langacker_marfatia_steigman_2003, title={Hiding relativistic degrees of freedom in the early universe}, volume={569}, ISSN={["1873-2445"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0041693919&partnerID=MN8TOARS}, DOI={10.1016/j.physletb.2003.07.039}, abstractNote={We quantify the extent to which extra relativistic energy density can be concealed by a neutrino asymmetry without conflicting with the baryon asymmetry measured by the Wilkinson Microwave Anisotropy Probe (WMAP). In the presence of a large electron neutrino asymmetry, slightly more than seven effective neutrinos are allowed by Big Bang Nucleosynthesis (BBN) and WMAP at 2\sigma. The same electron neutrino degeneracy that reconciles the BBN prediction for the primordial helium abundance with the observationally inferred value also reconciles the LSND neutrino with BBN by suppressing its thermalization prior to BBN.}, number={3-4}, journal={PHYSICS LETTERS B}, author={Barger, V and Kneller, JP and Langacker, P and Marfatia, D and Steigman, G}, year={2003}, month={Sep}, pages={123–128} }
 @article{kneller_strigari_2003, title={Inverse power law quintessence with nontracking initial conditions}, volume={68}, ISSN={["1550-2368"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0344875158&partnerID=MN8TOARS}, DOI={10.1103/physrevd.68.083517}, abstractNote={A common property of popular models of quintessence dark energy is the convergence to a common solution from a large range of the initial conditions. We reexamine the popular inverse power-law model of quintessence (where the common solution is dubbed as the ``tracker'') with particular attention to the initial conditions for the field and their influence on the evolution. We find that previously derived limits on the parameters of the potential in this model are valid only in a range of initial conditions. A reasonably sharp boundary lies where the initial energy density of the scalar field is equal to that of the background radiation component. An initial quintessence energy density above this equipartition value leads to a solution that will not have joined the tracker solution by the present epoch. These nontracker solutions possess the property that their present equation of state is very compatible with the observed bounds and independent of the exponent of the potential.}, number={8}, journal={PHYSICAL REVIEW D}, author={Kneller, JP and Strigari, LE}, year={2003}, month={Oct} }
 @article{kneller_phillips_walker_2003, title={Testing Two Nuclear Physics Approximations Used in the Standard Leaky‐Box Model for the Spallogenic Production of LiBeB}, volume={589}, url={http://dx.doi.org/10.1086/374592}, DOI={10.1086/374592}, abstractNote={The spallative production rates of lithium, beryllium, and boron (LiBeB) are a necessary component in any calculation of the evolution of these nuclei in the Galaxy. Previous calculations of these rates relied on two assumptions relating to the nuclear physics aspects: the straight-ahead approximation that describes the distribution of fragment energies and the assumption that the major contributor to the production rate arises from single-step reactions between primary cosmic-ray projectiles and interstellar medium targets. We examine both assumptions by using a semiempirical description for the spall's energy distribution and by including the reactions that proceed via intermediary fragments. After relaxing the straight-ahead approximation, we find that the changes in the production rates and emerging fluxes are small and do not warrant rejection of this approximation. In contrast, we discover that two-step reactions can alter the production rate considerably, leading to noticeable increases in the efficiency of producing the LiBeB nuclei. Motivated by this result, we introduce a cascade technique to compute the production rates exactly and find that the results differ only slightly from those of our two-step calculations. We thus conclude that terminating the reaction network at the two-step order is sufficiently accurate for current studies of spallation.}, number={1 I}, journal={The Astrophysical Journal}, author={Kneller, J.P. and Phillips, J.R. and Walker, T.P.}, year={2003}, month={May}, pages={217–224} }
 @inproceedings{steigman_kneller_zentner_2002, title={CMB (and other) challenges to BBN}, volume={12}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0347377313&partnerID=MN8TOARS}, booktitle={Revista Mexicana de Astronomia y Astrofisica: Serie de Conferencias}, author={Steigman, G. and Kneller, J.P. and Zentner, A.}, year={2002}, pages={265–271} }
 @article{kneller_steigman_walker_2001, title={How does the cosmic microwave background plus big bang nucleosynthesis constrain new physics?}, volume={64}, url={http://dx.doi.org/10.1103/physrevd.64.123506}, DOI={10.1103/physrevd.64.123506}, abstractNote={Recent cosmic microwave background (CMB) results from BOOMERANG, MAXIMA, and DASI provide cosmological constraints on new physics that can be competitive with those derived from Big Bang Nucleosynthesis (BBN). In particular, both CMB and BBN can be used to place limits on models involving neutrino degeneracy and additional relativistic degrees of freedom. However, for the case of the CMB, these constraints are, in general, sensitive to the assumed priors. We examine the CMB and BBN constraints on such models and study the sensitivity of ``new physics" to the assumed priors. If we add a constraint on the age of the universe ($t_0 \ga 11$ Gyr), then for models with a cosmological constant, the range of baryon densities and neutrino degeneracy parameters allowed by the CMB and BBN is fairly robust: $\eta_{10} = 6.0 \pm 0.6$, \deln $\la 6$, $\xi_e \la 0.3$. In the absence of new physics, models without a cosmological constant are only marginally compatible with recent CMB observations (excluded at the 93% confidence level).}, number={12}, journal={Physical Review D}, author={Kneller, J.P. and Steigman, G. and Walker, T.P.}, year={2001}, month={Nov}, pages={6} }
 @article{kneller_scherrer_steigman_walker_2001, title={How does the cosmic microwave background plus big bang nucleosynthesis constrain new physics?}, volume={64}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0035893714&partnerID=MN8TOARS}, number={12}, journal={Physical Review D}, author={Kneller, J.P. and Scherrer, R.J. and Steigman, G. and Walker, T.P.}, year={2001} }