53 research outputs found
Particlization with local event-by-event conservation laws
We present a sampling method for the transition from relativistic
hydrodynamics to particle transport, commonly referred to as particlization,
which preserves the local event-by-event conservation of energy, momentum,
baryon number, strangeness, and electric charge. The proposed method is
essential for studying fluctuations and correlations by means of stochastic
hydrodynamics. It is also useful for studying small systems. The method is
based on Metropolis sampling applied to particles within distinct patches of
the hypersurface, where hydrodynamics and kinetic evolutions are matched.Comment: 4 pages, 1 figur
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Microcanonical Particlization with Local Conservation Laws.
We present a sampling method for the transition from relativistic hydrodynamics to particle transport, commonly referred to as particlization, which preserves the local conservation of energy, momentum, baryon number, strangeness, and electric charge microcanonically, i.e., in every sample. The proposed method is essential for studying fluctuations and correlations by means of stochastic hydrodynamics. It is also useful for studying small systems. The method is based on Metropolis sampling applied to particles within distinct patches of the switching space-time surface, where hydrodynamic and kinetic evolutions are matched
Influence of kinematic cuts on the net charge distribution
The higher moments of the net charge distributions, e.g. the skewness and
kurtosis, are studied within an infinite hadronic matter calculation in a
transport approach. By dividing the box into several parts, the volume
dependence of the fluctuations is investigated. After confirming that the
initial distributions follow the expectations from a binomial distribution, the
influence of quantum number conservation in this case the net charge in the
system on the higher moments is evaluated. For this purpose, the composition of
the hadron gas is adjusted and only pions and mesons are simulated to
investigate the charge conservation effect. In addition, the effect of imposing
kinematic cuts in momentum space is analysed. The role of resonance excitations
and decays on the higher moments can also be studied within this model. This
work is highly relevant to understand the experimental measurements of higher
moments obtained in the RHIC beam energy scan and their comparison to lattice
results and other theoretical calculations assuming infinite matter.Comment: 4 pages, 8 figures, replaced with accepted version of proceedings for
Quark Matter 2015, small corrections to the text, better readable Fig.
Speed of sound and baryon cumulants in heavy-ion collisions
We present a method that may allow an estimate of the value of the speed of
sound as well as its logarithmic derivative with respect to the baryon number
density in matter created in heavy-ion collisions. To this end, we utilize
well-known observables: cumulants of the baryon number distribution. In
analyses aimed at uncovering the phase diagram of strongly interacting matter,
cumulants gather considerable attention as their qualitative behaviour along
the explored range of collision energies is expected to aid in detecting the
QCD critical point. We show that the cumulants may also reveal the behavior of
the speed of sound in the temperature and baryon chemical potential plane. We
demonstrate the applicability of such estimates within two models of nuclear
matter, and explore what might be understood from known experimental data.Comment: 6 pages, 3 figures; a few minor changes; published versio
Large proton cumulants from the superposition of ordinary multiplicity distributions
We construct a multiplicity distribution characterized by large factorial
cumulants (integrated correlation functions) from a simple combination of two
ordinary multiplicity distributions characterized by small factorial cumulants.
We find that such a model, which could be interpreted as representing two event
classes, reproduces the preliminary data for the proton cumulants measured by
the STAR collaboration at GeV very well. This model then predicts very
large values for the fifth and sixth order factorial cumulants, which can be
tested in experiment.Comment: 15 pages, 4 figures; comments and addendum (2 pages) adde
Sensitivity of Au+Au collisions to the symmetric nuclear matter equation of state at 2 -- 5 nuclear saturation densities
We demonstrate that proton and pion flow measurements in heavy-ion collisions
at incident energies ranging from 1 to 20 GeV per nucleon in the fixed target
frame can be used for an accurate determination of the symmetric nuclear matter
equation of state at baryon densities equal 2--4 times nuclear saturation
density . We simulate Au+Au collisions at these energies using a hadronic
transport model with an adjustable vector mean-field potential dependent on
baryon density . We show that the mean field can be parametrized to
reproduce a given density-dependence of the speed of sound at zero temperature
, which we vary independently in multiple density intervals
to probe the differential sensitivity of heavy-ion observables to the equation
of state at these specific densities. Recent flow data from the STAR experiment
at the center-of-mass energies GeV can be
described by our model, and a Bayesian analysis of these data indicates a hard
equation of state at and a possible phase transition at
. More data at GeV, as well as a more
thorough analysis of the model systematic uncertainties will be necessary for a
more precise conclusion.Comment: 26 pages, 18 figures, accepted to publication in Phys Rev C, minor
fixe
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