782 research outputs found
Possible links between the liquid-gas and deconfinement-hadronization phase transitions
It is commonly accepted that strongly interacting matter has several phase
transitions in different domains of temperature and baryon density. In this
contribution I discuss two most popular phase transitions which in principle
can be accessed in nuclear collisions. One of them, the liquid-gas phase
transition, is well established theoretically and studied experimentally in
nuclear multifragmentation reactions at intermediate energies. The other one,
the deconfinement-hadronization phase transition, is at the focus of present
and future experimental studies with relativistic heavy-ion beams at SPS, RHIC
and LHC. Pssible links between these two phase transitions are identified from
the viewpoint of their manifestation in violent nuclear collisions.Comment: 15 pages in revtex, 2 figures, to be published in the book "Dynamics
and Thermodynamics with Nuclear Degrees of Freedom" by Springe
Hydrodynamical modeling of the deconfinement phase transition and explosive hadronization
Dynamics of relativistic heavy-ion collisions is investigated on the basis of a simple (1+1)-dimensional hydrodynamical model in light-cone coordinates. The main emphasis is put on studying sensitivity of the dynamics and observables to the equation of state and initial conditions. Low sensitivity of pion rapidity spectra to the presence of the phase transition is demonstrated, and some inconsistencies of the equilibrium scenario are pointed out. Possible non-equilibrium effects are discussed, in particular, a possibility of an explosive disintegration of the deconfined phase into quark-gluon droplets. Simple estimates show that the characteristic droplet size should decrease with increasing the collective expansion rate. These droplets will hadronize individually by emitting hadrons from the surface. This scenario should reveal itself by strong non-statistical fluctuations of observables. Critical Point and Onset of Deconfinement 4th International Workshop July 9-13 2007 GSI Darmstadt,German
Studying Phase Transitions in Nuclear Collisions
In this talk I discuss three main topics concerning the theoretical
description and observable signatures of possible phase transitions in nuclear
collisions. The first one is related to the multifragmentation of thermalized
sources and its connection to a liquid-gas phase transition in finite systems.
The second one is dealing with the Coulomb excitation of ultrarelativistic
heavy ions resulting in their deep disintegration. The third topic is devoted
to the description of a first order phase transition in rapidly expanding
matter. The resulting picture is that a strong collective flow of matter will
lead to the fragmentation of a metastable phase into droplets. If the
transition from quark-gluon plasma to hadron gas is of the first order it will
manifest itself by strong nonstatistical fluctuations in observable hadron
distributions.Comment: Invited talk presented at the International Conference "Physics with
Storage Rings" (Bloomington, USA, 12-16 Sep. 1999), 16 pages in LaTeX
including 4 eps figures, fig. 1 in colo
Clusters of matter and antimatter
In this talk I first give a short overview of antinuclei production in recent
experiments at RHIC. Then I discuss the possibility of producing new types of
nuclear systems by implanting an antibaryon into ordinary nuclei. The structure
of nuclei containing one antiproton or antilambda is investigated within the
framework of a relativistic mean-field model. Self-consistent calculations
predict an enhanced binding and considerable compression in such systems as
compared with normal nuclei. I present arguments that the life time of such
nuclei with respect to the antibaryon annihilation might be long enough for
their observation. Few experimental signatures are suggested. Possible
formation of multi-quark-antiquark clusters is also discussed.Comment: 9 pages, 6 eps figures, invited talk at the VIII International
Conference on Nucleus-Nucleus Collisions (Moscow, 17-21 June 2003
Collective mechanism of dilepton production in high-energy nuclear collisions
Collective bremsstrahlung of vector meson fields in relativistic nuclear
collisions is studied within the time-dependent Walecka model. Mutual
deceleration of the colliding nuclei is described by introducing the effective
stopping time and average rapidity loss of baryons. It is shown that
electromagnetic decays of virtual omega-mesons produced by bremsstrahlung
mechanism can provide a substantial contribution to the soft dilepton yield at
the SPS bombarding energies. In particular, it may be responsible for the
dilepton enhancement observed in 160 AGev central Pb+Au collisions. Suggestions
for future experiments to estimate the relative contribution of the collective
mechanism are given.Comment: 6 page
Thermodynamics of dense hadronic matter in a parity doublet model
We study thermodynamics of nuclear matter in a two-flavored parity doublet
model within the mean field approximation. Parameters of the model are chosen
to reproduce correctly the properties of the nuclear ground state. The model
predicts two phase transitions in nuclear matter, a liquid-gas phase transition
at normal nuclear density and a chiral transition at higher density. At finite
temperature the pion decay constant exhibits a considerable reduction at
intermediate values of chemical potential, which is traced back to the presence
of the liquid-gas transition, and approaches zero at higher chemical potential
associated with the chiral symmetry restoration. A "transition" from meson-rich
to baryon-rich matter is also discussed.Comment: 7 pages, 4 figure
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