Modelling early stages of relativistic heavy-ion collisions

Abstract

In this study we model early time dynamics of relativistic heavy ion collisions by an initial color-electric field which then decays to a plasma by the Schwinger mechanism. The dynamics of the many particles system produced by the decay is described by relativistic kinetic theory, taking into account the backreaction on the color field by solving self-consistently the kinetic and the field equations. Our main results concern isotropization and thermalization for a 1 + 1D expanding geometry. In case of small η/s (η/s 0.3) we find τ isotropization ≈ 0.8 fm/c and τ thermalization ≈ 1 fm/c in agreement with the common lore of hydrodynamics.

Modeling early stages of relativistic heavy ion collisions: Coupling relativistic transport theory to decaying color-electric flux tubes

“…We have formulated transport theory in terms of a fixed value of η/s rather than scattering amplitude; in this way we are able to describe the evolution of the fluid in terms of macroscopic quantities (η/s) rather than insisting on a set of specific microscopic processes. The approach developed here, based on a stochastic solution of the relativistic Boltzman equation, has in perspective the advantage to be easily extended to 3 + 1D realistic simulations, allowing to study the possible impact of the early dynamics on observables like radial and elliptic flow [69]. Our study well matches [54] where the same problem has been studied.…”

“…Besides being the first study in which a Monte Carlo method is used to simulate the Schwinger effect in the context of early times dynamics of high energy collisions, we improve previous studies which mainly rely on Relaxation Time Approximation (RTA) [54,55] or on a linearization of the conductive electric current [45], by avoiding any ansatz both on the electric current and on the collision integral in the Boltzmann equation which permits to go beyond the RTA. The approach developed here, based on a stochastic solution of the relativistic Boltzman equation, has in perspective the advantage to be easily extended to 3 + 1D realistic simulations, allowing to study the possible impact of the early dynamics on observables like radial and elliptic flow [69].…”

Photons from the early stages of relativistic heavy-ion collisions

“…In this subection, we summarize the Abelian Flux Tube model (AFTm), that we use to define an initial condition in our simulations based on classical gluon fields, as well as the base for the evolution of this field configuration to QGP, see [27,28,[37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54] for details.…”

Thermalization of parton spectra in the colour-flux-tube model

“…We observe that the spectra have exponential, thermal-like shapes for all proper times and The low-p ⊥ enhancement is not observed in Ref. [63], where exclusively the gluon spectrum is considered. Left panels: The p ⊥ spectra of partons calculated using Eq.…”

“…[48] in a simpler framework of the color-flux-tubes model [49][50][51][52][53][54][55], where the color field dynamics is treated in the Abelian dominance approximation [56][57][58][59][60][61][62] (these results have been reproduced in Ref. [63] in the Monte-Carlo transport approach [64][65][66][67][68][69][70]). In Ref.…”