Nuclear Theory·nucl-th

Friday·February 14, 2020

8 papers—5 primary·3 cross-listed

01
Early thermalization and shear viscosity to entropy ratio in heavy-ion collisions at energies of BES, FAIR and NICA
E. Zabrodin🇳🇴 · L. Bravina🇳🇴 · M. Teslyk🇳🇴 · O. Vitiuk🇳🇴
Equilibration of highly excited baryon-rich matter is studied within the microscopic model calculations in A+A collisions at energies of BES, FAIR and NICA. It is shown that the system evolution from the very beginning of the collision can be approximated by relativistic hydrodynamics, although the hot and dense nuclear matter is not in local equilibrium yet. During the evolution of the fireball the extracted values of energy density, net baryon and net strangeness densities are used as an input to Statistical Model (SM) in order to calculate temperature $T$ , chemical potentials $μ_{B}$ and $μ_{S}$ , and entropy density $s$ of the system. Also, they are used as an input for the box with periodic boundary conditions to investigate the momentum correlators in the infinite nuclear matter. Shear viscosity $η$ is calculated according to the Green-Kubo formalism. At all energies, shear viscosity to entropy density ratio shows minimum at time corresponding to maximum baryon density. The ratio dependence on $T, μ_{B}, μ_{S}$ is investigated for both in- and out of equilibrium cases.
nucl-thhep-phnucl-exNPA(2021)·5 citations
02
Importance of non-flow background on the chiral magnetic wave search
Hao-jie Xu · Jie Zhao · Yicheng Feng · Fuqiang Wang
An observable sensitive to the chiral magnetic wave (CMW) is the charge asymmetry dependence of the $π^{-}$ and $π^{+}$ anisotropic flow difference, $Δ v_{n} (A_{ch})$ . We show that, due to non-flow correlations, the flow measurements by the Q-cumulant method using all charged particles as reference introduce a trivial linear term to $Δ v_{n} (A_{ch})$ . The trivial slope contribution to the triangle flow difference $Δ v_{3} (A_{ch})$ can be negative if the non-flow is dominated by back-to-back pairs. This can explain the observed negative $Δ v_{3} (A_{ch})$ slope in the preliminary STAR data. We further find that the non-flow correlations give rise to additional backgrounds to the slope of $Δ v_{2} (A_{ch})$ from the competition among different pion sources and from the larger multiplicity dilution to $π^{+}$ ( $π^{-}$ ) at positive (negative) $A_{ch}$ .
nucl-thNPA(2021)·9 citations
03
Revisiting Bayesian constraints on the transport coefficients of QCD
J.-F. Paquet🇺🇸 · A. Angerami · S. A. Bass · S. Cao · Y. Chen · J. Coleman · L. Cunqueiro · T. Dai · L. Du · R. Ehlers · H. Elfner · D. Everett and 38 other authors
Multistage models based on relativistic viscous hydrodynamics have proven successful in describing hadron measurements from relativistic nuclear collisions. These measurements are sensitive to the shear and the bulk viscosities of QCD and provide a unique opportunity to constrain these transport coefficients. Bayesian analyses can be used to obtain systematic constraints on the viscosities of QCD, through methodical model-to-data comparisons. In this manuscript, we discuss recent developments in Bayesian analyses of heavy ion collision data. We highlight the essential role of closure tests in validating a Bayesian analysis before comparison with measurements. We discuss the role of the emulator that is used as proxy for the multistage theoretical model. We use an ongoing Bayesian analysis of soft hadron measurements by the JETSCAPE Collaboration as context for the discussion.
nucl-thhep-phNPA(2021)·26 citations
04
Rotation Effects on Mesonic Condensations in Isospin Matter
Hui Zhang🇨🇳 · Defu Hou🇨🇳 · Jin-feng Liao🇺🇸
We investigate the rotation effects on the mesonic condensation in isospin matter . Using the two-flavor NJL effective model with a global rotation, we demonstrate two important effects of the rotation on its phase structure: a rotational suppression of the scalar-channel condensates, in particular the pion condensation region; and a rotational enhancement of the rho condensation region with vector-channel condensate. A new phase diagram for isospin matter under rotation is mapped out on the $ω - μ_{I}$ plane where three distinctive phases, corresponding to $σ$ , $π$ , $ρ$ dominated regions respectively, are separated by a second-order line at low isospin chemical potential and a first-order line at high rotation which are further connected at a tri-critical point.
nucl-thNPA(2021)·3 citations
05
Coexistence phase of $^{1} S_{0}$ and $^{3} P_{2}$ superfluids in neutron stars
Shigehiro Yasui🇯🇵 · Daisuke Inotani🇯🇵 · Muneto Nitta🇯🇵
In neutron star matter, there exist $^{1} S_{0}$ superfluids in lower density in the crust while $^{3} P_{2}$ superfluids are believed to exist at higher density deep inside the core. In the latter, depending on the temperature and magnetic field, either the uniaxial nematic phase, the D $_{2}$ -biaxial nematic phase, or the D $_{4}$ -biaxial nematic phase appears. In this paper, we discuss a mixture of the $^{1} S_{0}$ and $^{3} P_{2}$ superfluids and find their coexistence. Adopting the loop expansion and the weak-coupling approximation for the interaction between two neutrons, we obtain the Ginzburg-Landau (GL) free energy in which both of the $^{1} S_{0}$ and $^{3} P_{2}$ condensates are taken into account by including the coupling terms between them. We analyze the GL free energy and obtain the phase diagram for the temperature and magnetic field. We find that the $^{1} S_{0}$ superfluid excludes the $^{3} P_{2}$ superfluid completely in the absence of magnetic field, they can coexist for weak magnetic fields, and the $^{1} S_{0}$ superfluid is expelled by the $^{3} P_{2}$ superfluid at strong magnetic fields, thereby proving the robustness of $^{3} P_{2}$ superfluid against the magnetic field. We further show that the D $_{4}$ -BN phase covers the whole region of the $^{3} P_{2}$ superfluidity as a result of the coupling term, in contrast to the case of a pure $^{3} P_{2}$ superfluid studied before in which the D $_{4}$ -BN phase is realized only under strong magnetic fields. Thus, the D $_{4}$ -BN phase is topologically the most interesting phase, e.g., admitting half-quantized non-Abelian vortices relevant not only in magnetars but also in ordinary neutron stars.
nucl-thastro-ph.HEcond-mat.supr-conPRC(2020)·16 citations

Affiliations

first authorsco-authorsvia INSPIRE

Early thermalization and shear viscosity to entropy ratio in heavy-ion collisions at energies of BES, FAIR and NICA

Importance of non-flow background on the chiral magnetic wave search

Revisiting Bayesian constraints on the transport coefficients of QCD

Rotation Effects on Mesonic Condensations in Isospin Matter

Coexistence phase of 1S0​ and 3P2​ superfluids in neutron stars

Affiliations

Coexistence phase of $^{1} S_{0}$ and $^{3} P_{2}$ superfluids in neutron stars