Covariant description of kinetic freeze out through a finite space-like layer

The problem of Freeze Out (FO) in relativistic heavy ion reactions is addressed. We develop and analyze an idealized one-dimensional model of FO in a finite layer, based on the covariant FO probability. The resulting post FO phase-space distributions are discussed for different FO probabilities and layer thicknesses.Comment: 16 pages, 19 figures, changed content, references adde

Quark-Gluon Plasma Freeze-out from a Supercooled State?

We consider time-scales of first-order deconfinement or chiral-symmetry restoring phase transition in high energy heavy ion collisions at RHIC and LHC energies. Recently it was shown that the system must supercool below $T_c$ before the nucleation of hadronic bubbles is sufficiently rapid to overcome the expansion rate. It is shown here that the expected time-scales of high energy heavy ion reactions are sufficiently short to prevent the reheating of the system to near $T_c$. If quark-gluon plasma is produced in these collisions, it may have to hadronize from a supercooled state and the hadrons produced during rehadronization may freeze-out almost immediately.Comment: LaTeX, 14 pages + 2 eps figures. Contribution to the Proceedings of the Workshop on Preequilibrium Parton Dynamics, LBL, Aug. 199

Differential Hanbury-Brown-Twiss for an exact hydrodynamic model with rotation

We study an exact rotating and expanding solution of the fluid dynamical model of heavy ion reactions, that take into account the rate of slowing down of the rotation due to the longitudinal and transverse expansion of the system. The parameters of the model are set on the basis of realistic 3+1D fluid dynamical calculation at TeV energies, where the rotation is enhanced by the build up of the Kelvin Helmholtz Instability in the flow.Comment: 4 Pages, 7 figures, to be published in PR

Study of vorticity in an exact rotating hydro model

We study a semianalytic exact solution of the fluid dynamical model of heavy ion reactions, and evaluate some observable signs of the rotation.Comment: 19 pages, 6 figures. arXiv admin note: substantial text overlap with arXiv:1406.101

Time dependence of partition into spectators and participants in relativistic heavy-ion collisions

The process of formation of the participant system in heavy-ion collisions is investigated in the framework of a simplified analytic Glauber-like model, which is based on the relativistic Boltzmann transport equation. The key point lies in the time-dependent partition of the nucleon system into two groups: nucleons, which did not take part in any interaction before a given time and nucleons, which already have interacted. In the framework of the proposed model we introduce a natural energy-dependent temporal scale $t_c$, which allows us to remove all dependencies of the model on the collision energy except for the energy dependence of the nucleon-nucleon cross-section. By investigating the time dependence of the total number of participants we conclude that the formation process of the participant system becomes complete at $t\simeq1.5 t_c$. Time dependencies of participant total angular momentum and vorticity are also considered and used to describe the emergence of rotation in the reaction plane.Comment: 24 pages, 10 figures, minor changes to match published versio

Longitudinal fluctuations of the center of mass of the participants in heavy-ion collisions

A model for computing the probability density of event-by-event participant center-of-mass rapidity y^{c.m.} is presented. The evaluations of the y^{c.m.} distribution are performed for different collision energies and different centralities. We show that for certain conditions the rapidity distribution is described by a Gaussian with a variance determined mostly by the collision centrality. It is found that the width of the y^{c.m.} distribution increases strongly for more peripheral collisions, while it depends weakly on the collision energy. Other theoretical estimates of rapidity distribution are presented and questions of interaction and separation between spectators and participants are discussed.Comment: 8 pages, 9 figures, references added, minor changes to match published versio

Modified Boltzmann Transport Equation and Freeze Out

We study Freeze Out process in high energy heavy ion reaction. The description of the process is based on the Boltzmann Transport Equation (BTE). We point out the basic limitations of the BTE approach and introduce Modified BTE. The Freeze Out dynamics is presented in the 4-dimensional space-time in a layer of finite thickness, and we employ Modified BTE for the realistic Freeze Out description.Comment: 9 pages, 2 figure

Study of Rotating High Energy Systems with the Differential HBT Method

Peripheral heavy ion reactions at ultra relativistic energies have large angular momentum that can be studied via two particle correlations using the Differential Hanbury Brown and Twiss method. In the present work we analyze the possibilities and sensitivity of the method in rotating, few source systems. Analytic results provide insight in the advantages of this method.Comment: To be submitted to International Journal of Modern Physics E. arXiv admin note: substantial text overlap with arXiv:1305.038

Fluctuation and Dissipation in Classical Many-Particle Systems

Coarse-grained Langevin-type effective field equations are derived for classical systems of particles. These equations include the effects of thermal fluctuation and dissipation which may arise from coupling to an external bath, as in the Brownian motion of a single particle, or which may arise from statistical fluctuations in small parts of an isolated many-particle system, as in sound waves. These equations may provide some guidance for the analysis of mesoscopic or microscopic molecular systems, or for systems of hundreds to thousands of subatomic particles produced in high energy nuclear collisions.Comment: 16 pages in LaTe