A Calculation of the Viscosity to Entropy Ratio of a Hadronic Gas

We calculate thermodynamic quantities and transport coefficients of a hadronic gas using a Monte Carlo hadronic collision event generator URASiMA. The obtained shear viscosity to entropy density ratio of the hadronic gas is approximately 0.3 -- 0.6 in the range $T$ = 100 -- 180MeV and is quite insensitive to the baryon number density.Comment: 7 pages, 6 figure

Transverse momentum dependence of Hanbury Brown-Twiss radii of pions from a perfectly opaque source with hydrodynamic flow

We investigate the transverse momentum dependence of pion HBT radii on the basis of a hydrodynamical model. Recent experimental data show that $R_{\text{out}}/R_{\text{side}} < 1$, which suggests a strong opaqueness of the source. In addition to the opaqueness naturally caused by transverse flow, we introduce an extrinsic opacity by imposing restrictions on the pion emission angle. Comparing the HBT radii obtained from the normal Cooper-Frye prescription and the opaque emission prescription, we find that $R_{\text{out}}/R_{\text{side}}$ is less than unity only for small values of the transverse momentum with an opaque source. However, HBT radii for large values of the transverse momentum are dominated by the transverse flow effect and are affected less by the source opaqueness.Comment: 9 pages, 7 figures. 2 figures are added. To be published in Prog. Theor. Phy

Transport coefficients of the second order hydrodynamics and the applicability of hydrodynamic model

Based on the Nakajima-Zubarev type nonequilibrium density operator, we derive microscopic formulae of the transport coefficients in the second order hydrodynamics.Comment: 4pages, Contributed paper for the XLI International Symposium on Multiparticle Dynamics (ISMD2011

(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.Comment: 24 pages, 25 eps figures, LaTeX 2 epsilo

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.Comment: 5 pages, LaTeX, 7 EPS figures. Talk at the International School on the Physics of Quark Gluon Plasma, June 3-6, 1997, Hiroshima, Japa