相关论文: Nonequilibrium process in the $\sigma$ model and c…
We calculate characteristic time scales for chemical equilibration of pions in hot hadronic matter using an effective chiral Lagrangian. We find that inelastic processes involving the vector and axial vector mesons reduce the chemical…
We examine the non-equilibrium time evolution of the hadronic plasma produced in a relativistic heavy ion collision, assuming a spherical expansion into the vacuum. We study the $O(4)$ linear sigma model to leading order in a large-$N$…
Results of the computer simulation of dilepton production from the expanding pion gas created in ultrarelativistic Pb+Pb 160 GeV/n collisions are presented. Finite size of the expanding pion gas influences invariant mass spectrum of…
The relaxation times over which dissipative fluxes restore their steady state values have been evaluated for a pion gas using the 14-moment method. The effect of the medium has been implemented through a temperature dependent pi-pi…
We develop a kinetic equation approach to nonequilibrium pion and sigma meson production in a time-dependent, chiral symmetry breaking field (inertial mechanism). We investigate the question to what extent the low-momentum pion enhancement…
Using the O(4) linear $\sigma$ model, we address the topic of non-equilibrium relaxation of an inhomogeneous initial configuration due to quantum and thermal fluctuations. The space-time evolution of an inhomogeneous fluctuation of the…
The kinetic Freeze Out process of a pion gas through a finite layer with time-like normal is considered. The pion gas is described by a Boltzmann gas with elastic collisions among the pions. Within this model, the impact of the in-medium…
We extend our previous analysis of holographic heavy ion collisions in non-conformal theories. We provide a detailed description of our numerical code. We study collisions at different energies in gauge theories with different degrees of…
We calculate the pi-/pi+ ratio for Pb+Pb at CERN/SPS energies and for Au+Au at BNL/AGS energies using a (3+1) dimensional hydrodynamical model. Without consideration of Coulomb effect an enhancement of this ratio at low mt is found…
We are analyzing the hydrodynamics of 200 A GeV S+S collisions using a new approach which tries to quantify the uncertainties arising from the specific implementation of the hydrodynamical model. Based on a previous phenomenological…
Relaxation and correlation times are two parameters used frequently in approximate descriptions of the time development of hadronizing system from some initial state towards distributions observed experimentally. Chosen to reproduce the…
Within the context of the linear $\s$-model for two flavours, we investigate non-equilibrium phenomena that may occur during the QCD chiral phase transition in heavy-ion collisions. We assume that the chiral symmetry breaking is followed by…
We extend Chiral Perturbation Theory to study a meson gas out of thermal equilibrium. We assume that the system is initially in equilibrium at a temperature below the phase transition and work within a Schwinger-Keldysh contour technique.…
Thermodynamical variables and their time evolution are studied for central relativistic heavy ion collisions from 10.7 to 160 AGeV in the microscopic Ultrarelativistic Quantum Molecular Dynamics model (UrQMD). The UrQMD model exhibits…
We consider a non-ideal hot pion gas with the dynamically fixed number of particles in the model with the $\lambda\phi^4$ interaction. The effective Lagrangian for the description of such a system is obtained after dropping the terms…
We use a simple gas model to study non-equilibrium aspects of the multiparticle dynamics relevant to heavy ion collisions. By performing numerical simulations for various initial conditions we identify several characteristic features of the…
The presence of memory effects and color long-range forces among the many-parton system in the early stage of heavy-ion collisions can affect the particle statistical behavior at the freeze-out temperature. In this context, we calculate, in…
Following a relativistic heavy ion collision, the quark-gluon plasma produced eventually undergoes a chiral phase transition. We assume that during this phase transition one can describe the dynamics of the system by the linear $\sigma$…
We investigate the thermalization and the chemical equilibration of a parton plasma created from Au+Au collision at LHC and RHIC energies starting from the early moment when the particle momentum distributions in the central region become…
We consider an interacting pion gas in the regime where thermal but not chemical equilibrium has been reached. Approximate particle number conservation is implemented by a nonvanishing pion chemical potential $\mu_\pi$ within a diagrammatic…