Equilibration of the Quark-Gluon Plasma at finite net-baryon density in QCD kinetic theory

Abstract

We explore the out-of-equilibrium dynamics of the Quark-Gluon Plasma at zero and finite netbaryon density based on an effective kinetic theory of Quantum Chromo Dynamics (QCD). By investigating the isotropization of the longitudinal pressure, we determine the relevant time and temperature scales for the onset of viscous hydrodynamics, and quantify the dependence on the chemical composition of the QGP. By extrapolating our results to realistic coupling strength, we discuss phenomenological consequences regarding the role of the pre-equilibrium phase at different collision energies.

Intermediate mass dileptons as pre-equilibrium probes in heavy ion collisions

“…Despite the loss of thermal equilibrium, different microscopic simulations have shown that the evolution of the energy density and of the longitudinal pressure are fairly universal when expressed as a function of the dimensionless scaling variable [19,24] 14) and ( 15), as a function of w calculated in weak coupling regime with QCD kinetics [15,14]. Dashed lines correspond to the asymptotic behavior in (first order) viscous relativistic hydrodynamics.…”

“…With regards to describing the production of electromagnetic probes during the pre-equilibrium stage, two important effects must be taken into account. First of all, the initial stage is expected to be highly gluon dominated [11], and it takes time for quarks and antiquarks to be produced and reach thermal abundances [12,13,14,15]. Secondly, due to the rapid longitudinal expansion, the momentum distribution of quarks is strongly anisotropic at early times [8], with the typical transverse momenta larger than longitudinal momenta.…”

“…We use a sim-plified hydrodynamic modelization, in which the density is assumed to be uniformly distributed in the transverse plane. But we implement a state-of-the-art treatment of pre-equilibrium effects [14,15] (Sec. 3), which is essential since, as written above, dileptons probe the tail of the quark distribution.…”

Thermalization of non-abelian gauge theories at next-to-leading order

“…On the other hand, weak-coupling methods are available for generic theories and have also been widely studied. The first works studying thermalization of pure Yang-Mills theory from simple initial conditions [18] have been extended to * smi6nd@virginia.edu Quantum Chromodynamics (QCD) [19][20][21][22] and calculations based on this physical picture have been extended to describe systems of enough complexity to be used in realistic phenomenological modelling of heavy-ion collisions [23,24] and even in light-ion collisions [25]. This picture has also been applied to parametric estimates of thermalization times during reheating [26][27][28].…”

Convergence of hydrodynamic modes: insights from kinetic theory and holography

“…1 Kinetic theory can act as an effective description of processes in weakly-coupled quantum field theories when interference effects can be neglected [17,18]. In particular, the effective kinetic theory of QCD [19][20][21] has recently become a framework of significant theoretical and phenomenological interest in the context of ultrarelativistic heavy-ion collisions [22][23][24][25][26][27][28][29][30][31].…”