179 research outputs found
A calculation of the transport coefficients of hot and dense hadronic matter based on the event generator URASiMA
We evaluate thermodynamical quantities and the transport coefficients of a
dense and hot hadronic matter based on the event generator URASiMA
(Ultra-Relativistic AA collision Simulator based on Multiple Scattering
Algorithm) with periodic boundary conditions. As the simplest example of the
transport coefficients we investigate the temperature dependence and the
chemical potential dependence of the baryon diffusion constant of a dense and
hot hadronic matter.Comment: To appear in the Proceeding of the International Conference on Quark
Nuclear Physics(QNP2000), 21-25 February 2000, Adelaide, Australi
Analyses of collective flow and space-time evolution based on relativistic hydrodynamical model
We numerically solve fully (3+1)-dimensional relativistic hydrodynamical
equation with the baryon number conservation law. For realistic initial
conditions we adopt the results from the event generator (URASiMA). Using this
model we discuss collective flow.Comment: 4 pages, 11 figures, to apper in Proceedings of Quark Matter '9
Charge diffusion constant in hot and dense hadronic matter - A Hadro-molecular-dynamic calculation
We evaluate charge diffusion constant of dense and hot hadronic matter based
on the molecular dynamical method by using a hadronic collision generator which
describes nuclear collisions at energies 10 < E < 100 GeV/A and satisfies
detailed balance at low temperatures (T < 200 MeV). For the hot and dense
hadronic matter of the temperature range, 100 < T < 200 MeV and baryon number
density, 0.16 < nB < 0.32 fm^-3, charge diffusion constant D gradually
increases from 0.5 fm c to 2 fm c with temperature and is almost independent of
baryon number density. Based on the obtained diffusion constant we make simple
discussions on the diffusion of charge fluctuation in ultrarelativistic nuclear
collisions.Comment: 13 pages, 4 figure
A Calculation of Baryon Diffusion Constant in Hot and Dense Hadronic Matter Based on an Event Generator URASiMA
We evaluate thermodynamical quantities and transport coefficients of a dense
and hot hadronic matter based on an event generator URASiMA (Ultra-Relativistic
AA collision Simulator based on Multiple Scattering Algorithm). The statistical
ensembles in equilibrium with fixed temperature and chemical potential are
generated by imposing periodic boundary condition to the simulation of URASiMA,
where energy density and baryon number density is conserved. Achievement of the
thermal equilibrium and the chemical equilibrium are confirmed by the common
value of slope parameter in the energy distributions and the saturation of the
numbers of contained particles, respectively. By using the generated ensembles,
we investigate the temperature dependence and the chemical potential dependence
of the baryon diffusion constant of a dense and hot hadronic matter.Comment: 15 pages, 5 figures, LaTeX2
Non-Commutativity of the Zero Chemical Potential Limit and the Thermodynamic Limit in Finite Density Systems
Monte Carlo simulations of finite density systems are often plagued by the
complex action problem. We point out that there exists certain
non-commutativity in the zero chemical potential limit and the thermodynamic
limit when one tries to study such systems by reweighting techniques. This is
demonstrated by explicit calculations in a Random Matrix Theory, which is
thought to be a simple qualitative model for finite density QCD. The
factorization method allows us to understand how the non-commutativity, which
appears at the intermediate steps, cancels in the end results for physical
observables.Comment: 7 pages, 9 figure
Effective Model Approach to the Dense State of QCD Matter
The first-principle approach to the dense state of QCD matter, i.e. the
lattice-QCD simulation at finite baryon density, is not under theoretical
control for the moment. The effective model study based on QCD symmetries is a
practical alternative. However the model parameters that are fixed by hadronic
properties in the vacuum may have unknown dependence on the baryon chemical
potential. We propose a new prescription to constrain the effective model
parameters by the matching condition with the thermal Statistical Model. In the
transitional region where thermal quantities blow up in the Statistical Model,
deconfined quarks and gluons should smoothly take over the relevant degrees of
freedom from hadrons and resonances. We use the Polyakov-loop coupled
Nambu--Jona-Lasinio (PNJL) model as an effective description in the quark side
and show how the matching condition is satisfied by a simple ansatz on the
Polyakov loop potential. Our results favor a phase diagram with the chiral
phase transition located at slightly higher temperature than deconfinement
which stays close to the chemical freeze-out points.Comment: 8 pages, 4 figures; Talk at International Workshop on High Density
Nuclear Matter, Cape Town, South Africa, April 6-9, 201
General Structure of Relativistic Vector Condensation
We study relativistic massive vector condensation due to a non zero chemical
potential associated to some of the global conserved charges of the theory. We
show that the phase structure is very rich. More specifically there are three
distinct phases depending on the value of one of the zero chemical potential
vector self interaction terms. We also develop a formalism which enables us to
investigate the vacuum structure and dispersion relations in the spontaneously
broken phase of the theory. We show that in a certain limit of the couplings
and for large chemical potential the theory is not stable. This limit,
interestingly, corresponds to a gauge type limit often employed to economically
describe the ordinary vector mesons self interactions in QCD. We finally
indicate for which physical systems our analysis is relevant.Comment: RevTex4 14 pages,4 figure
Instantons and Scalar Multiquark States: From Small to Large N_c
We study scalar quark-anti-quark and two-quark-two-anti-quark correlation
functions in the instanton liquid model. We show that the instanton liquid
supports a light scalar-isoscalar (sigma) meson, and that this state is
strongly coupled to both and . The scalar-isovector
meson, on the other hand, is heavy. We also show that these properties
are specific to QCD with three colors. In the large limit the
scalar-isoscalar meson is not light, and it is mainly coupled to .Comment: 24 page
The Superfluid and Conformal Phase Transitions of Two-Color QCD
The phase structure of two-color QCD is examined as a function of the
chemical potential and the number of light quark flavors. We consider effective
Lagrangians for two-color QCD containing the Goldstone excitations, spin-one
particles and negative intrinsic parity terms. We discuss the possibility of a
conformal phase transition and the enhancement of the global symmetries as the
number of flavors is increased. The effects of a quark chemical potential on
the spin-one particles and on the negative intrinsic parity terms are analyzed.
It is shown that the phase diagram that is predicted by the linearly realized
effective Lagrangian at tree-level matches exactly that predicted by chiral
perturbation theory.Comment: ReVTeX, 23 pages, 3 figures. Discussion of vector condensation
extended, two figures added, references adde
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