734 research outputs found
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
Can supercooling explain the HBT puzzle?
Possible hadronization of supercooled QGP, created in heavy ion collisions at
RHIC and SPS, is discussed within a Bjorken hydrodynamic model. Such a
hadronization is expected to be a very fast shock-like process, what, if
hadronization coincides or shortly followed by freeze out, could explain a part
of the HBT puzzle, i.e. the flash-like particle emission
(). HBT data also show that the expansion time
before freeze out is very short (). In this work we discuss
question of supercooled QGP and the timescale of the reaction.Comment: 9 pages, 2 figure
Domain Wall Dynamics of Phase Interfaces
The statics and dynamics of a surface separating two phases of a relativistic
quantum field theory at or near the critical temperature typically make use of
a free energy as a functional of an order parameter. This free energy
functional also affords an economical description of states away from
equilibrium. The similarities and differences between using a scalar field as
the order parameter versus the energy density are examined, and a peculiarity
is noted. We also point out several conceptual errors in the literature dealing
with the dynamical prefactor in the nucleation rate.Comment: 12 pages plus 5 figure
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
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 . 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
Comment on "Exactly central heavy-ion collisions by nuclear hydrodynamics"
Problems arising in viscous nuclear fluid dynamical models of high-energy heavy-ion collisions are discussed. The importance of an accurate treatment of the transport properties of the hot and dense nuclear matter is pointed out
- âŠ