Quark production, Bose–Einstein condensates and thermalization of the quark–gluon plasma

2014/02/28 by Jean-Paul Blaizot, Bin Wu, Li Yan · 7 citations
Physics and Astronomy · #Cosmology and Gravitation Theories #High-Energy Particle Collisions Research #Quantum Chromodynamics and Particle Interactions #hep-ph #nucl-th

paper · pdf · doi:10.1016/j.nuclphysa.2014.07.041

published as Nucl.Phys. A930 (2014) 139-162 · 32 pages, 25 figures, minor modifications, Final version published in NPA

openalex publication_date 2014/08/04 · arxiv created 2014/10/22 · arxiv updated 2014/10/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

In this paper, we study the thermalization of gluons and N_f flavors of massless quarks and antiquarks in a spatially homogeneous system. First, two coupled transport equations for gluons and quarks (and antiquarks) are derived within the diffusion approximation of the Boltzmann equation, with only 2<-> 2 processes included in the collision term. Then, these transport equations are solved numerically in order to study the thermalization of the quark-gluon plasma. At initial time, we assume that no quarks or antiquarks are present and we choose the gluon distribution in the form f = f₀ theta (1-p/Q_s) with Q_s the saturation momentum and f₀ a constant. The subsequent evolution of systems may, or may not, lead to the formation of a (transient) Bose condensate, depending on the value of f₀. In fact, we observe, depending on the value of f₀, three different patterns: (a) thermalization without gluon Bose-Einstein condensate (BEC) for f₀ < f_0t, (b) thermalization with transient BEC for f_0t < f₀ < f_0c, and (c) thermalization with BEC for f_0c < f₀. The values of f_0t and f_0c depend on N_f. When f₀> 1 > f_0c, the onset of BEC occurs at a finite time t_c ~ 1/((alpha_s f₀)² Q_s). We also find that quark production slows down the thermalization process: the equilibration time for N_f = 3 is typically about 5 to 6 times longer than that for N_f = 0 at the same Q_s.

Citations

• On the equivalence between the Boltzmann equation and classical field theory at large occupation numbers
• From a colored glass condensate to the gluon plasma: Equilibration in high energy heavy ion collisions

Cited by

• Effective kinetic description of the expanding overoccupied glasma
• Properties of the Boltzmann equation in the classical approximation
• Nonequilibrium quark production in the expanding QCD plasma
• The thermalization of soft modes in non-expanding isotropic quark gluon plasmas
• Initialization of hydrodynamics in relativistic heavy ion collisions with an energy-momentum transport model
• Chemical equilibration in weakly coupled QCD
• Medium-induced fragmentation and equilibration of highly energetic partons

Related

• Quark production and thermalization of the quark-gluon plasma
• Thermalization and quark production in spatially homogeneous systems of gluons
• Thermalization of a Quark-Gluon Plasma
• A real-time lattice simulation of the thermalization of a gluon plasma: first results
• Quantum Transport Theory