@article{an_bluhm_du_dunne_elfner_gale_grefa_heinz_huang_karthein_et al._2022, title={The BEST framework for the search for the QCD critical point and the chiral magnetic effect}, volume={1017}, ISSN={["1873-1554"]}, DOI={10.1016/j.nuclphysa.2021.122343}, abstractNote={The Beam Energy Scan Theory (BEST) Collaboration was formed with the goal of providing a theoretical framework for analyzing data from the Beam Energy Scan (BES) program at the relativistic heavy ion collider (RHIC) at Brookhaven National Laboratory. The physics goal of the BES program is the search for a conjectured QCD critical point as well as for manifestations of the chiral magnetic effect. We describe progress that has been made over the previous five years. This includes studies of the equation of state and equilibrium susceptibilities, the development of suitable initial state models, progress in constructing a hydrodynamic framework that includes fluctuations and anomalous transport effects, as well as the development of freezeout prescriptions and hadronic transport models. Finally, we address the challenge of integrating these components into a complete analysis framework. This document describes the collective effort of the BEST Collaboration and its collaborators around the world.}, journal={NUCLEAR PHYSICS A}, author={An, Xin and Bluhm, Marcus and Du, Lipei and Dunne, Gerald V and Elfner, Hannah and Gale, Charles and Grefa, Joaquin and Heinz, Ulrich and Huang, Anping and Karthein, Jamie M. and et al.}, year={2022}, month={Jan} }
 @article{parotto_bluhm_mroczek_nahrgang_noronha-hostler_rajagopal_ratti_schafer_stephanov_2020, title={QCD equation of state matched to lattice data and exhibiting a critical point singularity}, volume={101}, ISSN={["2469-9993"]}, url={http://inspirehep.net/record/1672952}, DOI={10.1103/PhysRevC.101.034901}, abstractNote={We construct a family of equations of state for QCD in the temperature range 30MeV≤T≤800MeV and in the chemical potential range 0≤μB≤450MeV. These equations of state match available lattice QCD results up to O(μB4) and in each of them we place a critical point in the three-dimensional (3D) Ising model universality class. The position of this critical point can be chosen in the range of chemical potentials covered by the second Beam Energy Scan at the Relativistic Heavy Ion Collider. We discuss possible choices for the free parameters, which arise from mapping the Ising model onto QCD. Our results for the pressure, entropy density, baryon density, energy density, and speed of sound can be used as inputs in the hydrodynamical simulations of the fireball created in heavy ion collisions. We also show our result for the second cumulant of the baryon number in thermal equilibrium, displaying its divergence at the critical point. In the future, comparisons between RHIC data and the output of the hydrodynamic simulations, including calculations of fluctuation observables, built upon the model equations of state that we have constructed may be used to locate the critical point in the QCD phase diagram, if there is one to be found.}, number={3}, journal={PHYSICAL REVIEW C}, author={Parotto, Paolo and Bluhm, Marcus and Mroczek, Debora and Nahrgang, Marlene and Noronha-Hostler, J. and Rajagopal, Krishna and Ratti, Claudia and Schafer, Thomas and Stephanov, Mikhail}, year={2020}, month={Mar} }
 @article{nahrgang_bluhm_schafer_bass_2019, title={Diffusive dynamics of critical fluctuations near the QCD critical point}, volume={99}, ISSN={["1550-2368"]}, url={http://inspirehep.net/record/1667859}, DOI={10.1103/PhysRevD.99.116015}, abstractNote={A quantitatively reliable theoretical description of the dynamics of fluctuations in nonequilibrium is indispensable in the experimental search for the QCD critical point by means of ultrarelativistic heavy-ion collisions. In this paper we consider the fluctuations of the net-baryon density which becomes the slow, critical mode near the critical point. Due to net-baryon number conservation the dynamics is described by the fluid dynamical diffusion equation, which we extend to contain a white noise stochastic current. Including nonlinear couplings from the 3d Ising model universality class in the free energy functional, we solve the fully interacting theory in a finite size system. We observe that purely Gaussian white noise generates non-Gaussian fluctuations, but finite size effects and exact net-baryon number conservation lead to significant deviations from the expected behavior in equilibrated systems. In particular the skewness shows a qualitative deviation from infinite volume expectations. With this benchmark established we study the real-time dynamics of the fluctuations. We recover the expected dynamical scaling behavior and observe retardation effects and the impact of critical slowing down near the pseudocritical temperature.}, number={11}, journal={PHYSICAL REVIEW D}, author={Nahrgang, Marlene and Bluhm, Marcus and Schafer, Thomas and Bass, Steffen A.}, year={2019}, month={Jun} }
 @article{bluhm_nahrgang_bass_schafer_2017, place={Berkeley, United States}, title={Behavior of universal critical parameters in the QCD phase diagram}, volume={779}, ISSN={["1742-6596"]}, url={http://inspirehep.net/record/1503418}, DOI={10.1088/1742-6596/779/1/012074}, abstractNote={We determine the dependence of important parameters for critical fluctuations on temperature and baryon chemical potential in the QCD phase diagram. The analysis is based on an identification of the fluctuations of the order parameter obtained from the Ising model equation of state and the Ginzburg-Landau effective potential approach. The impact of the mapping from Ising model variables to QCD thermodynamics is discussed.}, number={1}, journal={16TH INTERNATIONAL CONFERENCE ON STRANGENESS IN QUARK MATTER (SQM2016)}, author={Bluhm, Marcus and Nahrgang, Marlene and Bass, Steffen A. and Schafer, Thomas}, year={2017} }
 @article{bluhm_hou_schafer_2017, title={Determination of the Density and Temperature Dependence of the Shear Viscosity of a Unitary Fermi Gas Based on Hydrodynamic Flow}, volume={119}, ISSN={["1079-7114"]}, url={http://inspirehep.net/record/1591363}, DOI={10.1103/physrevlett.119.065302}, abstractNote={We determine the shear viscosity of the ultracold Fermi gas at unitarity in the normal phase using hydrodynamic expansion data. The analysis is based on a generalized fluid dynamic framework which ensures a smooth transition between the fluid dynamic core of the cloud and the ballistic corona. We use expansion data taken by Joseph, Elliott, and Thomas [Shear Viscosity of a Universal Fermi Gas Near the Superfluid Phase Transition, Phys. Rev. Lett. 115, 020401 (2015).PRLTAO0031-900710.1103/PhysRevLett.115.020401] and measurements of the equation of state by Ku et al. [Revealing the superfluid lambda transition in the universal thermodynamics of a unitary Fermi gas, Science 335, 563 (2012).SCIEAS0036-807510.1126/science.1214987]. We find that the shear viscosity to particle density ratio just above the critical temperature is η/n|_{T_{c}}=0.41±0.11. We also obtain evidence that the shear viscosity to entropy density ratio has a minimum slightly above T_{c} with η/s|_{min}=0.50±0.10.}, number={6}, journal={PHYSICAL REVIEW LETTERS}, author={Bluhm, Marcus and Hou, Jiaxun and Schafer, Thomas}, year={2017}, month={Aug} }
 @article{bluhm_nahrgang_bass_schafer_2017, title={Impact of resonance decays on critical point signals in net-proton fluctuations}, volume={77}, ISSN={["1434-6052"]}, url={http://inspirehep.net/record/1502951}, DOI={10.1140/epjc/s10052-017-4771-3}, abstractNote={The non-monotonic beam energy dependence of the higher cumulants of net-proton fluctuations is a widely studied signature of the conjectured presence of a critical point in the QCD phase diagram. In this work we study the effect of resonance decays on critical fluctuations. We show that resonance effects reduce the signatures of critical fluctuations, but that for reasonable parameter choices critical effects in the net-proton cumulants survive. The relative role of resonance decays has a weak dependence on the order of the cumulants studied with a slightly stronger suppression of critical effects for higher-order cumulants.}, number={4}, journal={EUROPEAN PHYSICAL JOURNAL C}, author={Bluhm, Marcus and Nahrgang, Marlene and Bass, Steffen A. and Schafer, Thomas}, year={2017}, month={Apr} }
 @article{bluhm_schaefer_2016, title={Model-Independent Determination of the Shear Viscosity of a Trapped Unitary Fermi gas: Application to High-Temperature Data}, volume={116}, ISSN={["1079-7114"]}, url={http://inspirehep.net/record/1407992}, DOI={10.1103/physrevlett.116.115301}, abstractNote={Determinations of the shear viscosity of trapped ultracold gases suffer from systematic, uncontrolled uncertainties related to the treatment of the dilute part of the gas cloud. In this work we present an analysis of expansion experiments based on a new method, anisotropic fluid dynamics, that interpolates between Navier-Stokes fluid dynamics at the center of the cloud and ballistic behavior in the dilute corona. We validate the method using a comparison between anisotropic fluid dynamics and numerical solutions of the Boltzmann equation. We then apply anisotropic fluid dynamics to the expansion data reported by Cao et al. In the high-temperature limit we find η=0.282(mT)^{3/2}, which agrees within about 5% with the theoretical prediction η=0.269(mT)^{3/2}.}, number={11}, journal={PHYSICAL REVIEW LETTERS}, author={Bluhm, M. and Schaefer, T.}, year={2016}, month={Mar} }
 @article{alba_alberico_bellwied_bluhm_sarti_nahrgang_ratti_2015, title={Determination of freeze-out conditions from fluctuations in the Hadron Resonance Gas model}, volume={599}, ISSN={["1742-6596"]}, DOI={10.1088/1742-6596/599/1/012021}, abstractNote={Fluctuations of conserved charges measured in Heavy-Ion Collisions (HICs) received increasing attention in recent years, because they are good candidates to explore the phase diagram of QCD matter. During the last year, net-electric charge and net-proton moments of multiplicities measured at RHIC have been published by the STAR collaboration, for a range of collision energies which spans a region of the phase diagram at finite chemical potential. Here we present a new freeze-out curve obtained using the Hadron Resonance Gas (HRG) model approach to fit these experimental data. The HRG model is modified in order to have a realistic description of the HICs: kinematic cuts, resonance feed-down and resonance regeneration are taken into account. Our result is in agreement with preliminary studies by the ALICE collaboration, and is supported by a recent lattice analysis of the same quantities.}, journal={FAIRNESS 2014: FAIR NEXT GENERATION SCIENTISTS 2014}, author={Alba, P. and Alberico, W. and Bellwied, R. and Bluhm, M. and Sarti, V. Mantovani and Nahrgang, M. and Ratti, C.}, year={2015} }
 @article{bluhm_schaefer_2015, title={Dissipative fluid dynamics for the dilute Fermi gas at unitarity: Anisotropic fluid dynamics}, volume={92}, ISSN={["1094-1622"]}, url={http://inspirehep.net/record/1366213}, DOI={10.1103/physreva.92.043602}, abstractNote={We consider the time evolution of a dilute atomic Fermi gas after release from a trapping potential. A common difficulty with using fluid dynamics to study the expansion of the gas is that the theory is not applicable in the dilute corona, and that a naive treatment of the entire cloud using fluid dynamics leads to unphysical results. We propose to remedy this problem by including certain nonhydrodynamic degrees of freedom, in particular anisotropic components of the pressure tensor, in the theoretical description. We show that, using this method, it is possible to describe the crossover from fluid dynamics to ballistic expansion locally. We illustrate the use of anisotropic fluid dynamics by studying the expansion of the dilute Fermi gas at unitarity using different functional forms of the shear viscosity, including a shear viscosity that is solely a function of temperature, $\ensuremath{\eta}\ensuremath{\sim}{(mT)}^{3/2}$, as predicted by kinetic theory in the dilute limit.}, number={4}, journal={PHYSICAL REVIEW A}, author={Bluhm, M. and Schaefer, T.}, year={2015}, month={Oct} }
 @article{sarti_alba_alberico_bellwied_bluhm_nahrgang_ratti_2015, title={Fluctuations of conserved charges within a Hadron Resonance Gas approach: chemical freeze-out conditions from net-charge and net-proton fluctuations}, volume={97}, ISSN={["2100-014X"]}, DOI={10.1051/epjconf/20159700019}, abstractNote={We present an analysis of fluctuations of conserved charges, as baryon number B and electric charge Q , using the Hadron Resonance Gas (HRG) model. The study of such observables within a theoretical approach and the comparison to experimental data on the moments of the multiplicity distributions of specific particles represents a useful tool to extract the chemical freeze-out parameters, temperature T and baryo-chemical potential μ B . In particular we calculate ratios of higher-order susceptibilities for net-protons and net-charge and we compare our results to the latest data from STAR collaboration. The effect of resonance decays and kinematic cuts applied in the experimental analysis in transverse momentum, rapidity and pseudo-rapidity are included in the calculation along with the randomization of nucleons occurring in the hadronic phase.}, journal={RESONANCE WORKSHOP AT CATANIA}, author={Sarti, V. Mantovani and Alba, P. and Alberico, W. and Bellwied, R. and Bluhm, M. and Nahrgang, M. and Ratti, C.}, year={2015} }
 @article{sarti_alba_alberico_bellwied_bluhm_nahrgang_ratti_2015, title={Higher order fluctuations of strangeness and flavour hierarchy}, volume={599}, ISSN={["1742-6588"]}, DOI={10.1088/1742-6596/599/1/012022}, abstractNote={We present a preliminary analysis on the sensitivity to the chemical freeze-out temperature of higher order moments of strange particle multiplicity distributions in heavy ion collisions. Within the Hadron Resonance Gas (HRG) model we evaluate ratios of cumulants for kaons (K±) and hyperons (Λ, Σ±, Ξ−,0, Ω−) as a function of the temperature and compare them to the sensitivity profiles obtained from ratios of particle yields. We show that ratios of higher order fluctuations of strange baryons could provide a useful tool to extract the range of freeze-out temperature, once experimental data are available. Finally, a connection to lattice data through the fourth to second cumulant ratio is made. The deconfinement transition on the lattice seems to indicate the possibility of a flavour hierarchy, namely strange quarks seem to deconfine at a higher temperature. We would like to test the possibility for the same scenario to occur at the chemical freeze-out and we show how the inclusion of multi-strange baryons in the evaluation of higher order cumulants might provide a sensitive observable to extract the freeze-out temperature.}, journal={FAIRNESS 2014: FAIR NEXT GENERATION SCIENTISTS 2014}, author={Sarti, V. Mantovani and Alba, P. and Alberico, W. and Bellwied, R. and Bluhm, M. and Nahrgang, M. and Ratti, C.}, year={2015} }
 @article{nahrgang_bluhm_alba_bellwied_ratti_2015, title={Impact of resonance regeneration and decay on the net proton fluctuations in a hadron resonance gas}, volume={75}, ISSN={["1434-6052"]}, DOI={10.1140/epjc/s10052-015-3775-0}, abstractNote={We investigate net proton fluctuations as important observables measured in heavy-ion collisions within the hadron resonance gas (HRG) model. Special emphasis is given to effects which are a priori not inherent in a thermally and chemically equilibrated HRG approach. In particular, we point out the importance of taking into account the successive regeneration and decay of resonances after the chemical freeze-out, which lead to a randomization of the isospin of nucleons and thus to additional fluctuations in the net proton number. We find good agreement between our model results and the recent STAR measurements of the higher-order moments of the net proton distribution.}, number={12}, journal={EUROPEAN PHYSICAL JOURNAL C}, author={Nahrgang, Marlene and Bluhm, Marcus and Alba, Paolo and Bellwied, Rene and Ratti, Claudia}, year={2015}, month={Dec} }
 @article{bluhm_alba_alberico_bellwied_sarti_nahrgang_ratti_2015, title={Parametrization for chemical freeze-out conditions from net-charge fluctuations measured at RHIC}, volume={612}, ISSN={["1742-6596"]}, DOI={10.1088/1742-6596/612/1/012041}, abstractNote={We discuss details of our thermal model applied to extract chemical freeze-out conditions from fluctuations in the net-electric charge and net-proton number measured at RHIC. A parametrization for these conditions as a function of the beam energy is given.}, journal={HOT QUARKS 2014: WORKSHOP FOR YOUNG SCIENTISTS ON THE PHYSICS OF ULTRARELATIVISTIC NUCLEUS-NUCLEUS COLLISIONS}, author={Bluhm, M. and Alba, P. and Alberico, W. and Bellwied, R. and Sarti, V. Mantovani and Nahrgang, M. and Ratti, C.}, year={2015} }
 @article{alba_alberico_bluhm_greco_ratti_ruggieri_2015, title={Polyakov loop and gluon quasiparticles: A self-consistent approach to Yang-Mills thermodynamics}, volume={934}, ISSN={["1873-1554"]}, DOI={10.1016/j.nuclphysa.2014.11.011}, abstractNote={We present a quasiparticle model for the pure gauge sector of QCD, in which transverse quasigluons propagate in a Polyakov loop background field. By incorporating thermodynamic self-consistency in the approach, we show that our Polyakov loop extended quasiparticle model allows an accurate description of recent lattice results for all the thermodynamic quantities, including the Polyakov loop expectation value, in the deconfined phase. The related quasigluon mass exhibits a distinct temperature dependence, which is connected with the non-perturbative behavior seen in the scaled interaction measure of the pure gauge theory.}, journal={NUCLEAR PHYSICS A}, author={Alba, Paolo and Alberico, Wanda and Bluhm, Marcus and Greco, Vincenzo and Ratti, Claudia and Ruggieri, Marco}, year={2015}, month={Feb}, pages={41–51} }
 @article{alba_bellwied_bluhm_sarti_nahrgang_ratti_2015, title={Sensitivity of multiplicity fluctuations to freeze-out conditions in heavy ion collisions}, volume={92}, ISSN={["1089-490X"]}, DOI={10.1103/physrevc.92.064910}, abstractNote={We study the sensitivity of the higher-order moments of produced particle multiplicity distributions to the chemical freeze-out parameters in relativistic heavy ion collisions using the Hadron Resonance Gas (HRG) model. We compare the obtained sensitivity level to the one extracted from the ratios of particle yields. We find that, for certain final state hadrons, the fluctuation measurements add significant information to the determination of the hadro-chemical freeze-out properties of the deconfined phase of matter obtained at RHIC and the LHC.}, number={6}, journal={PHYSICAL REVIEW C}, author={Alba, Paolo and Bellwied, Rene and Bluhm, Marcus and Sarti, Valentina Mantovani and Nahrgang, Marlene and Ratti, Claudia}, year={2015}, month={Dec} }
 @article{bluhm_alba_alberico_bellwied_sarti_nahrgang_ratti_2014, title={Determination of freeze-out conditions from fluctuation observables measured at RHIC}, volume={931}, ISSN={["1873-1554"]}, DOI={10.1016/j.nuclphysa.2014.08.016}, abstractNote={We extract chemical freeze-out conditions via a thermal model approach from fluctuation observables measured at RHIC and compare with results from lattice QCD and statistical hadronization model fits. The possible influence of additional critical and non-critical fluctuation sources not accounted for in our analysis is discussed.}, journal={NUCLEAR PHYSICS A}, author={Bluhm, M. and Alba, P. and Alberico, W. and Bellwied, R. and Sarti, V. Mantovani and Nahrgang, M. and Ratti, C.}, year={2014}, month={Nov}, pages={814–819} }
 @article{alba_alberico_bellwied_bluhm_sarti_nahrgang_ratti_2014, title={Freeze-out conditions from net-proton and net-charge fluctuations at RHIC}, volume={738}, ISSN={["1873-2445"]}, DOI={10.1016/j.physletb.2014.09.052}, abstractNote={We calculate ratios of higher-order susceptibilities quantifying fluctuations in the number of net-protons and in the net-electric charge using the Hadron Resonance Gas (HRG) model. We take into account the effect of resonance decays, the kinematic acceptance cuts in rapidity, pseudo-rapidity and transverse momentum used in the experimental analysis, as well as a randomization of the isospin of nucleons in the hadronic phase. By comparing these results to the latest experimental data from the STAR Collaboration, we determine the freeze-out conditions from net-electric charge and net-proton distributions and discuss their consistency.}, journal={PHYSICS LETTERS B}, author={Alba, Paolo and Alberico, Wanda and Bellwied, Rene and Bluhm, Marcus and Sarti, Valentina Mantovani and Nahrgang, Marlene and Ratti, Claudia}, year={2014}, month={Nov}, pages={305–310} }
 @article{bluhm_schaefer_2014, title={Medium effects and the shear viscosity of the dilute Fermi gas away from the conformal limit}, volume={90}, ISSN={["1094-1622"]}, url={http://inspirehep.net/record/1321574}, DOI={10.1103/physreva.90.063615}, abstractNote={We study the shear viscosity of a dilute Fermi gas as a function of the scattering length in the vicinity of the unitarity limit. The calculation is based on kinetic theory, which provides a systematic approach to transport properties in the limit in which the fugacity $z=n\lambda^3/2$ is small. Here, $n$ is the density of the gas and $\lambda$ is the thermal wave length of the fermions. At leading order in the fugacity expansion the shear viscosity is independent of density, and the minimum shear viscosity is achieved at unitarity. At the next order medium effects modify the scattering amplitude as well as the quasi-particle energy and velocity. We show that these effects shift the minimum of the shear viscosity to the Bose-Einstein condensation (BEC) side of the resonance, in agreement with the result of recent experiments.}, number={6}, journal={PHYSICAL REVIEW A}, author={Bluhm, M. and Schaefer, T.}, year={2014}, month={Dec} }