1,380 research outputs found
Hadronization of Expanding QGP
We discuss how the dynamics of an exploding hot fireball of quark--gluon
matter impacts the actual phase transition conditions between the deconfined
and confined state of matter. We survey the chemical conditions prevailing at
hadronization.Comment: 8 pages, presented at QGPTH05, Vienna, August 200
Centrality Dependence of Bulk Fireball Properties at RHIC
We explore the centrality dependence of properties of the dense hadronic
matter created in \sqrt{s_{NN}}=200 GeV Au--Au collisions at RHIC. Using the
statistical hadronization model we fit particle yields known for 11 centrality
bins. We present the resulting model parameters, rapidity yields of physical
quantities and the physical properties of bulk matter at hadronization as
function of centrality. We discuss the production of strangeness and entropy.Comment: 7 pages including 5 figures, 1 table: more information provided:
figure 1 in lieu of work in progress defines phi-data, table for statistical
parameters for all models as function of centrality, additional references
and reference update, section captions, PRC `nearly to be published'.... look
out for further updates, referees run amoc
Quark-Gluon Plasma Fireball
Lattice-QCD results provide an opportunity to model, and extrapolate to
finite baryon density, the properties of the quark-gluon plasma (QGP). Upon
fixing the scale of the thermal coupling constant and vacuum energy to the
lattice data, the properties of resulting QGP equations of state (EoS) are
developed. We show that the physical properties of the dense matter fireball
formed in heavy ion collision experiments at CERN-SPS are well described by the
QGP-EoS we presented. We also estimate the properties of the fireball formed in
early stages of nuclear collision, and argue that QGP formation must be
expected down to 40A GeV in central Pb--Pb interactions.Comment: 10 pages, 9 postscript figures, 1 table, uses revtex, V3: introduced
difference between n_f and n_s; fireball restframe energy corrected,
references added. Publisched version in press Phys. Rev.
Strangeness Chemical Equilibration in QGP at RHIC and LHC
We study, in the dynamically evolving QGP fireball formed in relativistic
heavy ion collisions at RHIC and LHC, the growth of strangeness yield toward
and beyond the chemical equilibrium. We account for the contribution of the
direct strangeness production and evaluate the thermal-QCD strangeness
production mechanisms. The specific yield of strangeness per entropy, s/S, is
the primary target variable. We explore the effect of collision impact
parameter, i.e., fireball size, on kinetic strangeness chemical equilibration
in QGP. Insights gained in study the RHIC data with regard to the dynamics of
the fireball are applied to the study strangeness production at the LHC. We use
these results and consider the strange hadron relative particle yields at RHIC
and LHC in a systematic fashion. We consider both the dependence on s/S and
directly participant number dependence.Comment: 21 pages, 13 figures, PRC in press. Strangeness production recomputed
with K-factor K=1.7. Particle yields recomputed with SHARE 2.
Soft Hadron Ratios at the LHC
High precision soft hadron abundance data produced in relativistic nuclear
collisions at LHC at GeV will become available
beginning in 2007/8. We explore, within the statistical hadronization model,
how these results can help us understand the properties of the deconfined
quark--gluon phase at its breakup. We make assumptions about the physical
properties of the fireball and obtain particle production predictions. Then, we
develop a strategy to measure parameters of interest, such as strangeness
occupancy , chemical potentials and .Comment: 12 pages, 8 figures, v2: clarifications added, title simplified;
accepted for publication in the European Journal of Physics
Centrality dependence of strangeness and (anti)hyperon production at BNL RHIC
We evaluate strangeness produced in Au--Au interactions at
GeV, as function of reaction participant number ,
and obtain the relative strange quark content at hadronization. Strange baryon
and antibaryon rapidity density yields are studied, relative to, and as
function of, participant number, and produced hadron yields.Comment: 4 pages including 4 figures, v2 text improvmen
Gluon production, cooling and entropy in nuclear collisions
We study the cooling (heating) of a glue-parton gas due to production
(destruction) of particles and determine the associated production of entropy.
We incorporate sharing of the system energy among a changing number of
particles. We find that the entropy of an evolving glue-parton gas changes in
an insignificant range once the initial high temperature state has been formed,
despite a great change in particle number and temperature.Comment: Replaced for bad printing on US paper. 7 pages, LaTeX, 4 postscript
figure
The statistical hadronization model approach to GeV Au-Au collisions: -spectra fits and global variable predictions
Three possible scenarios of the statistical hadronization model are
reexamined with the use of the spectra of the PHENIX and very low
PHOBOS measurements at GeV. These scenarios are:
(\textit{a}) full chemical non-equilibrium, (\textit{b}) strangeness chemical
non-equilibrium and (\textit{c}) chemical equilibrium. Fits to the spectra are
done within the Cracow single-freeze-out model, which takes into account both
the expansion and resonance decays. Predictions for spectra of ,
and are also given. The global variables like the
transverse energy at midrapidity, the charged particle multiplicity at
midrapidity and the total multiplicity of charged particles are evaluated and
their predicted values agree qualitatively well with the experimental data. The
thorough analysis within this model suggests that the chemical full
non-equilibrium case is the least likely and both other cases are of the
similar likelihood. It is also shown that if the full chemical non-equilibrium
freeze-out took place it could manifest itself in the enhancement of the
-production at very low transverse momenta.Comment: 19 pages, 16 figures (included). This is the final version accepted
in Phys. Rev. C. Figs.9 and 10 have been changed since it turned out that the
data on \phi meson production were corrected for the branching ratio of \phi
decay into K_{+}K_{-
- âŠ