QCD at finite chemical potential in and out-of equilibrium
Olga Soloveva, Pierre Moreau, Elena Bratkovskaya
备注：
15 pages, 5 figures, contribution to the Proceedings of the 9th International Conference on New Frontiers in Physics (ICNFP 2020), 4 Sep.-2 Oct. 2020, Creta, Greece
We review the transport properties of the strongly interacting quark-gluon plasma (QGP) created in heavy-ion collisions at ultrarelativistic energies, i.e. out-of equilibrium, and compare them to the equilibrium properties. The description of the strongly interacting (non-perturbative) QGP in equilibrium is based on the effective propagators and couplings from the Dynamical QuasiParticle Model (DQPM) that is matched to reproduce the equation-of-state of the partonic system above the deconfinement temperature $T_c$ from lattice QCD. We study the transport coefficients such as the ratio of shear viscosity and bulk viscosity over entropy density, diffusion coefficients, electric conductivity etc. versus temperature and baryon chemical potential. Based on a microscopic transport description of heavy-ion collisions we, furthermore, discuss which observables are sensitive to the QGP formation and its properties.
The self-consistent mean field approximation of two-flavor NJL model with introducing a free parameter $α$ to reflect the competition between "direct" channel and the "exchange" channel, is employed to study QCD phase structure at finite isospin chemical potential $μ_I$, finite baryon chemical potential $μ_B$ and finite temperature $T$, especially the location of the QCD critical point. It is found that, for fixed isospin chemical potentials the lower temperature of phase transition is obtained with $α$ increasing in the $T-μ_I$ plane, and the largest difference of the phase transition tempera…
Constraining the QCD phase diagram by tricritical lines at imaginary chemical potential
我们从QCD的晶格模拟中得到了三种简并夸克在（T，m）相图中两个三临界点的明确证据，其中一个在轻质量区，另一个在重质量区，虚质量μ/T=iπ/3 mod 2π/3是固定的.这些代表的边界的手性和decenclosure临界线继续虚化学势，分别。结果表明，实化学势解禁闭临界线的形状是由三临界标度决定的，并意味着实化学势解禁闭跃迁的减弱.讨论了非简并夸克质量和轻夸克质量的推广。
Recent lattice QCD calculations strongly indicate that the chiral crossover of QCD at zero baryon chemical potential μ_B is a remnant of the second-order chiral phase transition. Universal properties of this second-order phase transition can be mapped to QCD temperature T and μ_B using non-universal parameters determined by lattice QCD recently. Motivated by these results, first, we discuss the analytic structure of the partition function in the QCD crossover regime - the so-called Yang-Lee edge singularity - solely based on universal properties. Next, utilizing the lattice QCD results for non…
We review the equation of state of QCD matter at finite densities. We discuss the construction of the equation of state with net baryon number, electric charge, and strangeness using the results of lattice QCD simulations and hadron resonance gas models. Its application to the hydrodynamic analyses of relativistic nuclear collisions suggests that the interplay of multiple conserved charges is important in the quantitative understanding of the dense nuclear matter created at lower beam energies. Several different models of the QCD equation of state are discussed for comparison.
Energy-loss of heavy quarks in the isotropic collisional hot QCD medium at a finite chemical potential
本文是{ \color{blue} Eur.物理学\ J. C { \bf 79}，761（2019）}中，我们研究了重夸克穿越各向同性碰撞热QCD介质的能量损失。随着反质子和离子研究所（FAIR）和基于核子的离子对撞机（NICA）等实验设施的建成，在有限重子密度和中等温度下探索QCD/QGP相图成为可能，有限化学势的引入对于研究热QCD/QGP介质是必要的。因此，我们的目标是发展一种形式来研究重夸克在相互作用的碰撞热QCD介质中运动的能量损失，该介质具有小的但有限的夸克化学势。为此，扩展的有效逸度准粒子模型已被采用\cite{chandra_quasi1, chandra_quasi2, Mitra:2017sjo}，而考虑有效的动力学理论方法使用的Bhatnagar-Gross-Krook（BGK）碰撞内核。最后，我们研究了在不同碰撞频率和化学势下，粲夸克和底夸克的能量损失与动量的关系。结果表明，与粲夸克相比，底夸克在特定的动量、碰撞频率和化学势下损失的能量更少。此外，能量损失被认为是随着化学势的增加而减少。
Taylor expansion of the equation of state of QCD suffers from shortcomings at chemical potentials $μ_B \geq (2-2.5)T$. First, one faces difficulties inherent in performing such an expansion with a limited number of coefficients; second, higher order coefficients determined from lattice calculations suffer from a poor signal-to-noise ratio. In this work, we present a novel scheme for extrapolating the equation of state of QCD to finite, real chemical potential that can extend its reach further than previous methods. We present continuum extrapolated lattice results for the new expansion coeffic…
