On correlations between charged and neutral particles in a cluster model

Abstract

Correlations between charged and neutral pions at high energies are investigated in the framework of a cluster model in which neutral clusters have a decay distribution determined by isospin conservation and statistical independence. For (n 0 )n_ an asymptotic expansion around the mean (n) leading asymptotically to a quadratic form in n_ is derived and compared with data.Recent experiments [ 1,2] have provided data on correlations between charged and neutral pions in inelastic high-energy scattering and it seems now worthwile to obtain representative fits for the various theoretical concepts.In this note we study the cluster model [3] in which independently produced neutral clusters [4] decay isotropically in their rest frames. Following the standard picture with factorized momentum and mass dependence of the cluster formation one can write the generating function for the multiplicity distribution simply aswhere (N c) is the average number of central clusters. G D is the generating function for the decay, which is obtained after averaging over the cluster masses and which is assumed to be energy independent. To avoid many parameters the presence of the leading particles and the special behaviour of the fragmentation cluster is disregarded. Existing work [5 ] which only takes into account a fixed cluster decay multiplicity seems no longer compatible with data and one has to turn to a suitable multiplicity distribution [6]. For this purpose we assume an approximate Poisson distribution for the total cluster decay multiplicities. In order to determine the ratios