8,220 research outputs found
From chemical freezeout to critical conditions in heavy ion collisions
We compare the statistical thermodynamics of hadron resonance gas with recent
LGT results at finite chemical potential. We argue that for the
equation of state derived from
Monte--Carlo simulations of two quark--flavor QCD at finite chemical
potential is consistent with that of a hadron resonance gas when applying the
same set of approximations as used in LGT calculations.
We indicate the relation of chemical freezeout conditions obtained from a
detailed analysis of particle production in heavy ion collisions with the
critical conditions required for deconfinement. We argue that the position of a
hadron--quark gluon boundary line in temperature chemical potential plane can
be determined in terms of the resonance gas model by the condition of fixed
energy density.Comment: Talk given at BUDAPEST'2004 Workshop on 'Hot and Dense Matter in
Relativistic Heavy Ion Physics', Budapest, March 24-27, 200
The Statistical Model of Hadrogenesis in A--A collisions from AGS to SPS and RHIC
We discuss experimental data on particle yields and particle spectra obtained
in heavy ion collisions in a very broad energy range from SIS/GSI through
AGS/BNL up to SPS/CERN and RHIC/BNL. We argue that in this broad energy range
hadronic yields and their ratios resemble a thermal equilibrium population
along a unified freeze--out curve determined by the condition of fixed
energy/particle = 1 GeV. At RHIC and top SPS, thermal parameters are consistent
within error with the critical conditions required for deconfinement. This,
together with the particular distribution of strangeness within a collision
fireball, could indicate that chemical equilibrium is a direct consequence of
parton to hadron transition, which populates a state of maximum entropy. At
lower energies equilibration in A--A collisions should appear through hadronic
interactions and rescatterings.Comment: Plenary talk given at: International Nuclear Physics Conference,
INPC2001, Berkeley, USA, August 200
Unbalanced Allocations
We consider the unbalanced allocation of balls into bins by a
randomized algorithm using the "power of two choices". For each ball, we select
a set of bins at random, then place the ball in the fullest bin within the set.
Applications of this generic algorithm range from cost minimization to
condensed matter physics. In this paper, we analyze the distribution of the bin
loads produced by this algorithm, considering, for example, largest and
smallest loads, loads of subsets of the bins, and the likelihood of bins having
equal loads
Thermodynamics of Van der Waals Fluids with quantum statistics
We consider thermodynamics of the van der Waals fluid of quantum systems. We
derive general relations of thermodynamic functions and parameters of any ideal
gas and the corresponding van der Waals fluid. This provides unambiguous
generalization of the classical van der Waals theory to quantum statistical
systems. As an example, we apply the van der Waals fluid with fermi statistics
to characterize the liquid-gas critical point in nuclear matter. We also
introduce the Bose-Einstein condensation in the relativistic van der Waals
boson gas, and argue, that it exhibits two-phase structure separated in space
Strangeness enhancement and Energy dependence in Heavy Ion Collisions
The canonical statistical model analysis of strange and multistrange hadron
production in central A-A relative to p-p/p-A collisions is presented over the
energy range from GeV up to GeV. It is shown that
the relative enhancement of strange particle yields from p-p/p-A to A-A
collisions substantially increases with decreasing collision energy. It is
largest at GeV, where the enhancement of and
is of the order of 100, 20 and 3, respectively. In terms of the model
these results are due to the canonical suppression of particle thermal phase
space at lower energies, which increases with the strangeness content of the
particle and with decreasing size of the collision fireball. The comparison of
the model with existing data on energy dependence of the kaon/pion ratio is
also discussed
Thermodynamics of the low density excluded volume hadron gas
We consider thermodynamics of the excluded volume particles at finite
temperature and chemical potential, in the low density approximation. We assume
Boltzmann statistics and study the influence of the excluded volume on an ideal
gas thermodynamics at the same temperature, pressure and numbers of particles.
We show, that considering the change of the free enthalpy due to the excluded
volume, and using the Maxwell identities, one can derive relevant thermodynamic
functions and parameters of multi-component gases. The derivation is quite
general as particles may have different sizes and shapes which can also depend
on their momenta. Besides it's simplicity and generality, our approach has the
advantage of eliminating the transcendental equations occurring in earlier
studies. A representative example of the excluded volume thermodynamics is the
single-component gas of hard spheres. For this case, using the viral expansion,
the validity limits of the low-density approximation are also discussed.Comment: 7 pages, 4 figur
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