arXiv subjects

Tetsufumi Hirano

Publications and source records attributed to Tetsufumi Hirano.

97 records · Page 6Linked to original sources

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.

nucl-th↗

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↗

arXiv2001

Is early thermalization achieved only near midrapidity at RHIC ?

The pseudorapidity dependence of elliptic flow in Au+Au collisions at 130 $A$ GeV is studied within a full three-dimensional hydrodynamic model in the light-cone coordinate. First, we prepare two initial conditions in the hydrodynamic model for analyzing elliptic flow. Both initial conditions lead to reasonable agreement with single particle spectra in central and semi-central collisions. Next, by using these hydrodynamic simulations, we compare elliptic flow as a function of pseudorapidity with experimental data recently measured by the PHOBOS Collaboration. Our results are in agreement with experimental data only near midrapidity. This suggests that thermalization in the early stage of collisions is not achieved in forward and backward rapidity regions.

nucl-th↗

arXiv2000

Hydrodynamic analysis of non-central Pb+Pb collisions at 158A GeV

We analyze non-central heavy-ion collisions at the relativistic energy within a full (3+1) dimensional hydrodynamic model. First, the initial parameters in the hydrodynamic model are chosen so that we reproduce the experimental data of both the rapidity distribution and the slope of transverse mass distribution in central Pb + Pb collisions at 158 $A$ GeV at the CERN SPS. We next study the validity of the ansatz of wounded nucleon scaling for the initial condition of the hydrodynamic model through analysis of the rapidity distribution of negative pions in non-central collisions. Moreover, a simple Monte Carlo method is introduced to exactly calculate the particle distribution from resonance decays.

nucl-th↗

arXiv2000

In-Plane Elliptic Flow of Resonance Particles in Relativistic Heavy-Ion Collisions

We analyze the second Fourier coefficient $v_2$ of the pion azimuthal distribution in non-central heavy-ion collisions in a relativistic hydrodynamic model. The exact treatment of the decay kinematics of resonances leads to almost vanishing azimuthal anisotropy of pions near the midrapidity, while the matter elliptic flow is in-plane at freeze-out. In addition, we reproduce the rapidity dependence of $v_2$ for pions measured in non-central Pb + Pb collisions at 158$A$ GeV. This suggests that resonance particles as well as stable particles constitute the in-plane flow and are important ingredients for the understanding of the observed pion flow.

nucl-th↗

arXiv1999

Elliptic Flow Based on a Relativistic Hydrodynamic Model

Based on the (3+1)-dimensional hydrodynamic model, the space-time evolution of hot and dense nuclear matter produced in non-central relativistic heavy-ion collisions is discussed. The elliptic flow parameter v_2 is obtained by Fourier analysis of the azimuthal distribution of pions and protons which are emitted from the freeze-out hypersurface. As a function of rapidity, the pion and proton elliptic flow parameters both have a peak at midrapidity.

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↗