Quantum number conservation in statistical models and its application top $$\bar p$$ -annihilatoin at rest

Abstract

We investigate the role of exact quantum number conservation in small statistical systems and illustrate the consequences forp $$\bar p$$ -annihililation at rest. A group theoretical projection method is used to calculate a restricted canonical partition function which consists only of states allowed by the conservation laws. Special emphasis is put on the conservation of isospin, total angular momentum, andC-, G-, andP-parities. Our analysis of the partition function shows that it is increasingly dominated by two-particle states as more of the conservation laws are included. The constraining effects on various multiplicity ratios and the deviations from the unconstrained limit are discussed in detail.