783 research outputs found
Relativistic Kinetic Equations for Finite Domains and Freeze-out Problem
The relativistic kinetic equations for the two domains separated by the
hypersurface with both space- and time-like parts are derived. The particle
exchange between the domains separated by the time-like boundaries generates
source terms and modifies the collision term of the kinetic equation. The
correct hydrodynamic equations for the ``hydro+cascade'' models are obtained
and their differences from existing freeze-out models of the hadronic matter
are discussed
Physical mechanism of the (tri)critical point generation
We discuss some ideas resulting from a phenomenological relation recently
declared between the tension of string connecting the static quark-antiquark
pair and surface tension of corresponding cylindrical bag. This relation
analysis leads to the temperature of vanishing surface tension coefficient of
the QGP bags at zero baryonic charge density as T_\sigma = 152.9 +- 4.5 MeV. We
develop the view point that this temperature value is not a fortuitous
coincidence with the temperature of (partial) chiral symmetry restoration as
seen in the lattice QCD simulations. Besides, we argue that T_\sigma defines
the QCD (tri)critical endpoint temperature and claim that a negative value of
surface tension coefficient recently discovered is not a sole result, but
should also exist in ordinary liquids at the supercritical temperatures.Comment: Talk given at the Conference "Critical Point and Onset of
Deconfinement (CPOD)" that held on August 23 - 29, 2010, JINR, Dubna, Russia.
Contains minimal change
Exactly Solvable Model for the QCD Tricritcal Endpoint
An inclusion of temperature and chemical potential dependent surface tension
into the gas of quark-gluon bags model resolves a long standing problem of a
unified description of the first and second order phase transition with the
cross-over. The suggested model has an exact analytical solution and allows one
to rigorously study the vicinity of the critical endpoint of the deconfinement
phase transition. It is found that at the curve of a zero surface tension
coefficient there must exist the surface induced phase tranition of the 2-nd or
higher order. The present model predicts that the critical endpoint (CEP) of
quantum chromodynamics is the tricritical endpoint.Comment: 14 pages, 3 figures, invited talk given at the International Workshop
``Relativistic Nuclear Physics: from Nuclotron to LHC Energies'', Kiev,
Ukraine, June 18-22, 200
Particle Freeze-out and Discontinuities in Relativistic Hydrodynamics
Freeze-out of particles in relativistic hydrodynamics is considered across a
3-dimensional space-time hypersurface. The conservation laws for time-like
parts of the freeze-out hypersurface require different values of temperature,
baryonic chemical potential and flow velocity in the fluid and in the final
particle spectra. We analyze this freeze-out discontinuity and its connection
to the shock-wave phenomena in relativistic hydrodynamics.Comment: 6 figure
Exactly Solvable Models: The Road Towards a Rigorous Treatment of Phase Transitions in Finite Systems
We discuss exact analytical solutions of a variety of statistical models
recently obtained for finite systems by a novel powerful mathematical method,
the Laplace-Fourier transform. Among them are a constrained version of the
statistical multifragmentation model, the Gas of Bags Model and the Hills and
Dales Model of surface partition. Thus, the Laplace-Fourier transform allows
one to study the nuclear matter equation of state, the equation of state of
hadronic and quark gluon matter and surface partitions on the same footing. A
complete analysis of the isobaric partition singularities of these models is
done for finite systems. The developed formalism allows us, for the first time,
to exactly define the finite volume analogs of gaseous, liquid and mixed phases
of these models from the first principles of statistical mechanics and
demonstrate the pitfalls of earlier works. The found solutions may be used for
building up a new theoretical apparatus to rigorously study phase transitions
in finite systems. The strategic directions of future research opened by these
exact results are also discussed.Comment: Contribution to the ``World Consensus Initiative III, Texas A & M
University, College Station, Texas, USA, February 11-17, 2005, 21
Asymptotic Regge Trajectories of Non-strange Mesons
We analyze the asymptotic behavior of Regge trajectories of non-strange
mesons. In contrast to an existing belief, it is demonstrated that for the
asymptotically linear Regge trajectories the width of heavy hadrons cannot
linearly depend on their mass. Using the data on masses and widths of rho_J,
omega_J, a_J and f_J mesons for the spin values J \leq 6, we extract the
parameters of the asymptotically linear Regge trajectory predicted by the
finite width model of quark gluon bags. As it is shown the obtained parameters
for the data set B correspond to the cross-over temperature lying in the
interval 170.9-175.3 MeV which is consistent with the kinetic freeze-out
temperature of early hadronizing particles found in relativistic heavy ion
collisions at and above the highest SPS energy.Comment: 14 pages, 3 figure
Hadron Spectra and QGP Hadronization in Au+Au Collisions at RHIC
The transverse mass spectra of Omega hyperons and phi mesons measured
recently by STAR Collaboration in Au+Au collisions at sqrt(s_NN) = 130 GeV are
described within a hydrodynamic model of the quark gluon plasma expansion and
hadronization. The flow parameters at the plasma hadronization extracted by
fitting these data are used to predict the transverse mass spectra of J/psi and
psi' mesons.Comment: 4 pages, 4 figures, Fig. 3 correcte
Specific heat at constant volume in the thermodynamic model
A thermodynamic model for multifragmentation which is frequently used appears
to give very different values for specific heat at constant volume depending
upon whether canonical or grand canonical ensemble is used. The cause for this
discrepancy is analysed.Comment: Revtex, 7 pages including 4 figure
Model of multifragmentation, Equation of State and phase transition
We consider a soluble model of multifragmentation which is similar in spirit
to many models which have been used to fit intermediate energy heavy ion
collision data. We draw a p-V diagram for the model and compare with a p-V
diagram obtained from a mean-field theory. We investigate the question of
chemical instability in the multifragmentation model. Phase transitions in the
model are discussed.Comment: Revtex, 9 pages including 6 figures: some change in the text and Fig.
About possible contribution of intrinsic charm component to inclusive spectra of charmed mesons
We calculate differential energy spectra (-distributions) of charmed
particles produced in proton-nucleus collisions, assuming the existence of
intrinsic heavy quark components in the proton wave function. For the
calculation, the recently proposed factorization scheme is used, based on the
Color Glass Condensate theory and specially suited for predictions of a
production of particles with large rapidities. It is argued that the intrinsic
charm component can, if it exists, dominate in a sum of two components,
intrinsic + extrinsic, of the inclusive spectrum of charmed particles produced
in proton-nucleus collisions at high energies, in the region of medium ,
, and can give noticeable contribution to atmospheric fluxes
of prompt muons and neutrinos.Comment: 10 pages, 4 figures. Version published in J. Phys. G
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