Multiplicity dependence of identical particle correlations in the quantum optical approach.pdf

a r X i v : h e p - p h / 9 9 0 7 3 4 8 v 1 1 4 J u l 1 9 9 9 Multiplicity Dependence of Identical Particle Correlations in the Quantum Optical Approach N. Suzuki and M. Biyajima? Matsusho Gakuen Junior College, Matsumoto 390-1295, Japan ?Department of physics, Shinshu University, Matsumoto 390-8621, Japan Abstract Identical particle correlations at fixed multiplicity are considered in the pres- ence of chaotic and coherent fields. The multiplicity distribution, one-particle momentum density and two-particle correlation function are obtained based on the diagrammatic representation for cumulants in semi-inclusive events. Our formulation is applied to the analysis of the experimental data on the multi- plicity dependence of correlation functions reported by the UA1 and the OPAL Collaborations. 1 Introduction In high energy hadron-hadron collisions, Bose-Einstein correlations of the identical particles are considered as one of the possible measures for the space-time domain where identical particles are produced. One of the theoretical approaches to the Bose-Einstein correlations is made on the analogy of the quantum optics [1], where two types of sources, chaotic and coherent are introduced. A diagrammatical method, based on the Glauber-Lachs formula [1], has been proposed [2] to find the higher order Bose-Einstein correlation (BEC) functions in the quantum optical (QO) approach. In Ref. [3], the generating functional (GF) for momentum densities is derived in the QO approach, and a diagrammatic representation for cumulants is proposed. Up to the present, identical particle correlations in fixed multiplicity events are investigated in the case of purely chaotic field. Two-particle correlations are analyzed in Ref. [4] by using Monte Carlo methods. Multiplicity dependence of one-particle distributions is discussed in Ref. [5], and that of two or three-particle correlations are considered in Ref. [6]. In Ref. [7], an outline of our formulation on the particle corre