Analysis of transverse momentum distributions observed at RHIC by a stochastic model in hyp.pdfVIP

3 0 Analysis of transverse momentum distributions observed at 0 RHIC by a stochastic model in hyperbolic space∗ 2 v N. Suzuki o N Department of Comprehensive Management, Matsumoto University, Matsumoto, 2 Japan 1 and 1 v M. Biyajima 2 5 Department of Physics, Shinshu University, Matsumoto, Japan 1 1 1 3 0 To describe large momentum distributions of charged hadrons observed / h at RHIC, a diffusion equation in the three dimensional hyperbolic space is p introduced. - p e PACS numbers: 25.75.-9, 25.75.Dw, 02.50.Ey h : v 1. Introduction i X We are much intersted in events with high multiplicity at RHIC, where r a thousands of particles are produced per event. To describe such many parti- cle system, a sort of collective approach will be useful. One-particle rapidity or pseudo-rapidity distributions observed at RHIC are well described by the Ornstein-Uhlenbeck process with two or three sources [1]. In this paper, we would extend our approach to include an expansion for transverse direction. We can derive the formula same with that proposed by Voloshin [2] from the three-dimensional Ornstein-Uhlenbeck process using the variables, lon- gitudinal rapidity and two transverse momenta. The fundamental solution is gaussian in these variables. Even if the formula is