352 research outputs found
Relativistic hydrodynamics with strangeness production
The relativistic hydrodynamic approach is used to describe production of
strangeness and/or heavy quarks in ultrarelativistic heavy ion reactions.
Production processes are important ingredients of dissipative effects in the
hadronic liquid. Beyond viscosity also chemo- and thermo-diffusion processes
are considered. This also allows to specify chemical and thermal freeze-out
conditions.Comment: v.2 with minor editorial corrections, 7 pages, talk given on the
SQM2007 conference, Levoca, June 24-29, 2007. To appear in the proceceeding:
Journal of Physics
Probability distributions in statistical ensembles with conserved charges
The probability distributions for charged particle numbers and their densities are derived in statistical ensembles with conservation laws. It is shown that if this limit is properly taken, then the canonical and grand canonical ensembles are equivalent. This equivalence is proven on the most general probability distribution level
The Best Predictions in Experimental Biology are Critical and Persuasive
A powerful way to evaluate scientific explanations (hypotheses) is to test the predictions that they make. In this way, predictions serve as an important bridge between abstract hypotheses and concrete experiments. Experimental biologists, however, generally receive little guidance on how to generate quality predictions. Here, we identify two important components of good predictions – criticality and persuasiveness – which relate to the ability of a prediction (and the experiment it implies) to disprove a hypothesis or to convince a skeptic that the hypothesis has merit. Using a detailed example, we demonstrate how striving for predictions that are both critical and persuasive can speed scientific progress by leading us to more powerful experiments. Finally, we provide a quality control checklist to assist students and researchers as they navigate the hypothetico-deductive method from puzzling observations to experimental tests
Entropy Production in Relativistic Hydrodynamics
The entropy production occurring in relativistic hydrodynamical systems such
as the quark-gluon plasma (QGP) formed in high-energy nuclear collisions is
explored. We study mechanisms which change the composition of the fluid, i.e.
particle production and/or chemical reactions, along with chemo- and
thermo-diffusion. These effects complement the conventional dissipative effects
of shear viscosity, bulk viscosity, and heat conductivity.Comment: 15 pages; LaTex. Accepted for publication in Physics Letters B. - Two
typos corrected and one reference adde
Probability distributions in statistical ensembles with conserved charges
The probability distributions for charged particle numbers and their
densities are derived in statistical ensembles with conservation laws. It is
shown that if this limit is properly taken then the canonical and grand
canonical ensembles are equivalent. This equivalence is proven on the most
general, probability distribution level.Comment: 5 pages. A little bit shorter version due to some editorial and
language changes. To be published in Phys. Rev.
Properties of an equilibrium hadron gas subjected to the adiabatic longitudinal expansion
We consider an ideal gas of massive hadrons in thermal and chemical
equilibrium. The gas expands longitudinally in an adiabatic way. This evolution
for a baryonless gas reduces to a hydrodynamic expansion. Cooling process is
parametrized by the sound velocity. The sound velocity is temperature dependent
and is strongly influenced by hadron mass spectrum.Comment: 7pages, 7 figures-- uucoded file of figures appended at the end,
separated from the paper by lines with many dashe
The canonical partition function for relativistic hadron gases
Particle production in high-energy collisions is often addressed within the
framework of the thermal (statistical) model. We present a method to calculate
the canonical partition function for the hadron resonance gas with exact
conservation of the baryon number, strangeness, electric charge, charmness and
bottomness. We derive an analytical expression for the partition function which
is represented as series of Bessel functions. Our results can be used directly
to analyze particle production yields in elementary and in heavy ion
collisions. We also quantify the importance of quantum statistics in the
calculations of the light particle multiplicities in the canonical thermal
model of the hadron resonance gas.Comment: 10 pages, 2 figures; submitted for publication in EPJ
Pion Number Fluctuations and Correlations in the Statistical System with Fixed Isospin
The statistical system of pions with zero total isospin is studied. The
suppression effects for the average yields due to isospin conservation are the
same for , and . However, a behavior of the corresponding
particle number fluctuations are different. For neutral pions there is the
enhancement of the fluctuations, whereas for charged pions the isospin
conservation suppresses fluctuations. The correlations between the numbers of
charged and neutral pions are observed for finite systems. This causes a
maximum of the total pion number fluctuations for small systems. The
thermodynamic limit values for the scaled variances of neutral and charged
pions are calculated. The enhancements of the fluctuations due to Bose
statistics are found and discussed
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