arXiv subjects

Shin Muroya

Publications and source records attributed to Shin Muroya.

28 records · Page 2Linked to original sources

arXiv2002

Comparison of space-time evolutions of hot/dense matter in $\sqrt{s_{NN}}$=17 and 130 GeV relativistic heavy ion collisions based on a hydrodynamical model

Based on a hydrodynamical model, we compare 130 GeV/$A$ Au+Au collisions at RHIC and 17 GeV/$A$ Pb+Pb collisions at SPS. The model well reproduces the single-particle distributions of both RHIC and SPS. The numerical solution indicates that huge amount of collision energy in RHIC is mainly used to produce a large extent of hot fluid rather than to make a high temperature matter; longitudinal extent of the hot fluid in RHIC is much larger than that of SPS and initial energy density of the fluid is only 5% higher than the one in SPS. The solution well describes the HBT radii at SPS energy but shows some deviations from the ones at RHIC.

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arXiv2002

Study of the Finite Density State based on SU(2) Lattice QCD

We report our recent numerical studies on two-color QCD with Wilson fermions. First the phase structure of the system in (kappa,mu)-plane is analyzed by measuring Polyakov line, baryon number density, gluon energy density and Polyakov line susceptibility. Then meson and baryon (di-quark) propagators are investigated. We find that the vector meson mass decreases near mu_c. This phenomena can be related to the low-mass lepton-pair enhancement observed in CERES experiment. Since our lattice is small, in order to confirm the results, we calculate both periodic and anti-periodic boundary condition cases. Preliminary calculations of color averaged, symmetric and anti-symmetric forces of qq system obtained from Polyakov line correlations, and gluon propagators are reported.

hep-lat↗

arXiv2002

Hydrodynamical analysis of hadronic spectra in the 130 GeV/nucleon Au+Au collisions

We study one-particle spectra and a two-particle correlation function in the 130 GeV/nucleon Au+Au collisions at RHIC by making use of a hydrodynamical model. We calculate the one-particle hadronic spectra and present the first analysis of Bose-Einstein correlation functions based on the numerical solution of the hydrodynamical equations which takes both longitudinal and transverse expansion into account appropriately. The hydrodynamical model provides excellent agreement with the experimental data in the pseudorapidity and the transverse momentum spectra of charged hadrons, the rapidity dependence of anti-proton to proton ratio, and almost consistent result for the pion Bose-Einstein correlation functions. Our numerical solution with simple freeze-out picture suggests the formation of the quark-gluon plasma with large volume and low net-baryon density.

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arXiv2002

Analysis of one- and two-particle spectra at RHIC based on a hydrodynamical model

We calculate the one-particle hadronic spectra and correlation functions of pions based on a hydrodynamical model. Parameters in the model are so chosen that the one-particle spectra reproduce experimental results of $\sqrt{s}=130A$GeV Au+Au collisions at RHIC. Based on the numerical solution, we discuss the space-time evolution of the fluid. Two-pion correlation functions are also discussed. Our numerical solution suggests the formation of the quark-gluon plasma with large volume and low net baryon density.

hep-ph↗

arXiv2000

(3+1)-dimensional relativistic hydrodynamical expansion of hot and dense matter in ultra-relativistic nuclear collision

A full (3+1)-dimensional calculation using the Lagrangian hydrodynamics is proposed for relativistic nuclear collisions. The calculation enables us to evaluate anisotropic flow of hadronic matter which appears in non-central and/or asymmetrical relativistic nuclear collisions. Applying hydrodynamical calculations to the deformed uranium collisions at AGS energy region, we discuss the nature of space-time structure and particle distributions in detail.

hep-ph↗

arXiv2000

Two-particle correlation from a relativistic fluid with a first order phase transition

We numerically calculate two-particle correlation functions of CERN-SPS 158 A GeV Pb+Pb central collisions based on a (3+1)-dimensional relativistic hydrodynamics with a first order phase transition. We analyze the pair momentum dependence of pion source sizes extracted from the Yano-Koonin-Podgoretski\uı (YKP) parametrization which is expected to give the source sizes directly. We find that, even in the case of the first order phase transition, the collective expansion and surface dominant freeze-out of the fluid naturally lead to the opaque source for which the interpretation of the temporal source parameter as the emission duration breaks down.

hep-ph↗

arXiv1999

Numerical analysis of two-pion correlation based on a hydrodynamical model

We will numerically investgate two-particle correlation function of CERN--SPS 158 A GeV Pb+Pb central collisions in detail based on a (3+1)-dimensional relativistic hydrodynamical model with first order phase transition. We use the Yano-Koonin-Podgoretski\uı parametrization as well as the usual Cartesian parametrization and analyze the pair momentum dependence of HBT radii extracted from the parametrizations. We find that the interpretation of the temporal radius parameters as the time duration in YKP parametrization is not available for the hydrodynamical model where the source became opaque naturally because of expansion and surface dominant freeze-out. Finally, effect of the phase transition on the source opacity is also discussed.

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arXiv1997

HBT Effect Based on a Hydrodynamical Model

We investigate HBT radii based on the numerical solutions of the hydrodynamical model which are so tuned as to reproduce the recent experimental data at the CERN SPS. Comparing the sizes of freeze-out hypersurface with HBT radii, we discuss dynamical effect of the systematic flow on the apparent HBT radii. Finally we compare HBT radii of the QGP phase transition model with those of the hadron gas model without phase transition.

nucl-th↗

arXiv1997

Transverse Photon Spectrum from QGP Fluid

We calculate the thermal photon distribution from the hot QCD matter produced by high energy nuclear collisions based on a hydrodynamical model, and compare it with the recent experimental data obtained by CERN WA80. Through the asymptotic value of the slope parameter of the transverse momentum distribution, we investigate the characteristic temperature of the QCD fluid.

nucl-th↗

arXiv1995

Numerical Analyses of CERN 200GeV/A Heavy-Ion Collisions Based on a Hydrodynamical Model with Phase Transition

We numerically analyze recent high energy heavy-ion collision experiments based on a hydrodynamical model with phase transition and discuss a systematic change of initial state of QGP-fluid depending on colliding-nuclei's mass. In a previous paper, we formulated a (3+1)-dimensional hydrodynamical model for quark-gluon plasma with phase transition and discussed numerically the space-time evolution in detail. We here compare the numerical solution with the hadronic distributions given by CERN WA80 and NA35. Systematic analyses of the experiments with various colliding nuclei enable us to discuss the dependences of the initial parameters of the hydrodynamical model on colliding nuclei's mass. Furthermore, extrapolating the present experiments, we derive the possible hadronic distributions for lead-lead 150GeV/A collision.

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