8,576 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 $T\leq T_c$ 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 $m$ balls into $n$ 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 $\sqrt s=8.73$ GeV up to $\sqrt s =130$ 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 $\sqrt s= 8.7$ GeV, where the enhancement of $\Omega,\Xi$ and
$\Lambda$ 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

### Momentum scale dependence of the net quark number fluctuations near chiral crossover

We investigate properties of the net baryon number fluctuations near chiral
crossover in a hot and dense medium of strongly interacting quarks. The
chirally invariant quark-antiquark interactions are modeled by an effective
quark-meson Lagrangian. To preserve remnants of criticality in the O(4)
universality class, we apply the functional renormalization group method to
describe thermodynamics near chiral crossover. Our studies are focused on the
influence of the momentum cuts on the critical behavior of different cumulants
of the net quark number fluctuations. We use the momentum scale dependence of
the flow equation to examine how the suppression of the momentum modes in the
infrared and ultraviolet regime modifies generic properties of fluctuations
expected in the O(4) universality class. We show, that the pion mass $m_\pi$ is
a natural soft momentum scale at which cumulants are saturated at their
critical values, whereas for scales larger than $2m_\pi$ the characteristic
O(4) structure of the higher order cumulants get lost. These results indicate,
that when measuring fluctuations of the net baryon number in heavy ion
collisions to search for a partial restoration of chiral symmetry or critical
point, a special care have to be made when introducing kinematical cuts on the
fluctuation measurements.Comment: 15 pages, 8 figures. To appear in Prog. Theor. Exp. Phy

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