5,090 research outputs found
Critical line of the deconfinement phase transition
Phase diagram of strongly interacting matter is discussed within the exactly
solvable statistical model of the quark-gluon bags. The model predicts two
phases of matter: the hadron gas at a low temperature T and baryonic chemical
potential muB, and the quark-gluon gas at a high T and/or muB. The nature of
the phase transition depends on a form of the bag mass-volume spectrum (its
pre-exponential factor), which is expected to change with the muB/T ratio. It
is therefore likely that the line of the 1st} order transition at a high muB/T
ratio is followed by the line of the 2nd order phase transition at an
intermediate muB/T, and then by the lines of "higher order transitions" at a
low muB/T.Comment: 13 pages, 6 figure
Strangeness Production in Light and Intermediate size Nucleus-Nucleus Collisions
Within the statistical model, the net strangeness conservation and incomplete
total strangeness equilibration lead to the suppression of strange particle
multiplicities. Furthermore, suppression effects appear to be stronger in small
systems. By treating the production of strangeness within the canonical
ensemble formulation we developed a simple model which allows to predict the
excitation function of ratio in nucleus-nucleus collisions. In
doing so we assumed that different values of , measured in p+p and
Pb+Pb interactions at the same collision energy per nucleon, are driven by the
finite size effects only. These predictions may serve as a baseline for
experimental results from NA61/SHINE at the CERN SPS and the future CBM
experiment at FAIR
Baryon number conservation and statistical production of antibaryons
The statistical production of antibaryons is considered within the canonical ensemble formulation. We demonstrate that the antibaryon suppression in small systems due to the exact baryon number conservation is rather different in the baryon-free (B=0) and baryon-rich (B>1) systems. At constant values of temperature and baryon density in the baryon-rich systems the density of the produced antibaryons is only weakly dependent on the size of the system. For realistic hadronization conditions this dependence appears to be close to B/(B+1) which is in agreement with the preliminary data of the NA49 Collaboration for the antiproton/pion ratio in nucleus-nucleus collisions at the CERN SPS energies. However, a consistent picture of antibaryon production within the statistical hadronization model has not yet been achieved. This is because the condition of constant hadronization temperature in the baryon-free systems leads to a contradiction with the data on the antiproton/pion ratio in e+e- interactions
Thermalization through Hagedorn states - the importance of multiparticle collisions
Quick chemical equilibration times of hadrons within a hadron gas are
explained dynamically using Hagedorn states, which drive particles into
equilibrium close to the critical temperature. Within this scheme master
equations are employed for the chemical equilibration of various hadronic
particles like (strange) baryon and antibaryons. A comparison of the Hagedorn
model to recent lattice results is made and it is found that for both Tc =176
MeV and Tc=196 MeV, the hadrons can reach chemical equilibrium almost
immediately, well before the chemical freeze-out temperatures found in thermal
fits for a hadron gas without Hagedorn states.Comment: 8 pages, 3 figures, talk presented at the International Conference on
Strangeness in Quark Matter, Buzios, Rio de Janeiro, Brazil, Sept. 27 - Oct.
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