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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.PACS numbers: 24.10. Nz, 12.38.Mh, 25.75.Gz Relativistic heavy ion collisions are very attracting problems which provide us the nature of hot and dense hadronic matter [1]. Creation of a new state of the matter, the quark-gluon plasma (QGP), and many kinds of new phenomena are expected to be found in the Relativistic Heavy Ion Collider (RHIC) experiments at BNL of which the collision energy is much higher than any other accelerator. However, the complicated processes during the many-body interactions and multiparticle productions are quite hard to catch clear. Therefore, a simple phenomenological description is indispensable for the better understanding of the phenomena. The aims of this paper are, based on a hydrodynamical model, to draw a simple and clear picture of the space-time evolution of the hot and dense matter produced in the high energy heavy ion collisions at RHIC and to give a possible explanation for the recent experimental results.We use a (3+1)-dimensional hydrodynamical model [2] to describe the space-time evolution assuming the local thermal and chemical equilibrium. , where main theme of the analysis is also anisotropic flow. In this paper, we focus our discussion on central collisions by assuming the cylindrical symmetry of the system. 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 [2].The hydrodynamical equations are given as ∂ µ T µν (x) = 0 with the baryon number conservation law ∂ µ n µ B (x) = 0. We numerically solve these coupled equations for the perfect fluid by the method described in Ref. [2]. Our numerical solution keeps entropy, energy and net baryon number conserved within 5% of accuracy throughout the calculation with the time step δτ = 0.01 fm/c. As for an equation of state (EOS), we adopt a bag model EOS in which phase transition of first order takes place [7]. The QGP phase is a free gas with a bag constant B. The gas consists of massless quarks of three flavor and gluons. The hadronic phase is a free resonance g...

We investigate the two-particle intensity correlation function of in relativistic heavy-ion collisions. We find that the behavior of the correlation function at small relative momenta is fairly sensitive to the interaction potential and collective flows. By comparing the results of different source functions and potentials, we explore the effect of intrinsic collective motions on the correlation function. We find that the recent STAR data give a strong constraint on the scattering length and effective range of interaction, as −1.8 fm −1 < 1/a 0 < −0.8 fm −1 and 3.5 fm < r eff < 7 fm, respectively, if samples do not include the feed-down contribution from long-lived particles. We find that the feed-down correction for 0 decay reduces the sensitivity of the correlation function to the detail of the interaction. As a result, we obtain a weaker constraint, 1/a 0 < −0.8 fm −1 . Implication for the signal of existence of H -dibaryon is discussed. Comparison with the scattering parameters obtained from the double hypernucleus may reveal in-medium effects in the interaction.