725 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
Fluctuations and the QCD Phase Diagram
In this contribution we will discuss how the study of various fluctuation
observables may be used to explore the phase diagram of the strong interaction.
We will briefly summarize the present study of experimental and theoretical
research in this area. We will then discuss various corrections and issues
which need to be understood and applied for a meaningful comparison of
experimental measurements with theoretical predictions. This contribution is
dedicated to Andrzej Bialas on the occasion of his birthday.Comment: Conference Proceeding
Fluidity and supercriticality of the QCD matter created in relativistic heavy ion collisions
In this paper we discuss the fluidity of the hot and dense QCD matter created
in ultrarelativistic heavy ion collisions in comparison with various other
fluids, and in particular suggest its possible supercriticality. After
examining the proper way to compare non-relativistic and relativistic fluids
from both thermodynamic and hydrodynamic perspectives, we propose a new
fluidity measure which shows certain universality for a remarkable diversity of
critical fluids. We then demonstrate that a fluid in its supercritical regime
has its fluidity considerably enhanced. This may suggest a possible
relationship between the seemingly good fluidity of the QCD matter produced in
heavy ion collisions at center of mass energy of and
the supercriticality of this matter with respect to the Critical-End-Point on
the QCD phase diagram. Based on such observation, we predict an even better
fluidity of the matter to be created in heavy ion collisions at LHC energy and
the loss of good fluidity at certain lower beam energy. Finally based on our
criteria, we analyze the suitability of a hydrodynamic description for the
fireball evolution in heavy ion collisions at various energies.Comment: 12 pages, 6 figures; minor corrections; final version published in
PR
Effect of finite particle number sampling on baryon number fluctuations
The effects of finite particle number sampling on the net baryon number
cumulants, extracted from fluid dynamical simulations, are studied. The
commonly used finite particle number sampling procedure introduces an
additional Poissonian (or multinomial if global baryon number conservation is
enforced) contribution which increases the extracted moments of the baryon
number distribution. If this procedure is applied to a fluctuating fluid
dynamics framework one severely overestimates the actual cumulants. We show
that the sampling of so called test-particles suppresses the additional
contribution to the moments by at least one power of the number of
test-particles. We demonstrate this method in a numerical fluid dynamics
simulation that includes the effects of spinodal decomposition due to a first
order phase transition. Furthermore, in the limit where anti-baryons can be
ignored, we derive analytic formulas which capture exactly the effect of
particle sampling on the baryon number cumulants. These formulas may be used to
test the various numerical particle sampling algorithms.Comment: 9 pages 3 figure
Net-baryon multiplicity distribution consistent with lattice QCD
We determine the net-baryon multiplicity distribution which reproduces all
cumulants measured so far by lattice QCD. We present the dependence on the
volume and temperature of this distribution. We find that for temperatures and
volumes encountered in heavy ion reactions, the multiplicity distribution is
very close to the Skellam distribution, making the experimental determination
of it rather challenging. We further provide estimates for the statistics
required to measure cumulants of the net-baryon and net-proton distributions.Comment: 13 pages, 6 figures; Extended version. Now include statistics
estimate for RHIC and LHC based on delta metho
Rapidity dependence of proton cumulants and correlation functions
The dependence of multi-proton correlation functions and cumulants on the
acceptance in rapidity and transverse momentum is studied. We find that the
preliminary data of various cumulant ratios are consistent, within errors, with
rapidity and transverse momentum independent correlation functions. However,
rapidity correlations which moderately increase with rapidity separation
between protons are slightly favored. We propose to further explore the
rapidity dependence of multi-particle correlation functions by measuring the
dependence of the integrated reduced correlation functions as a function of the
size of the rapidity window.Comment: 13 pages, 5 figure
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