QUANTUM-STATISTICAL SPACE-TIME APPROACH TO BOSE-EINSTEIN CORRELATIONS AND MULTIPLICITY DISTRIBUTIONS

A systematic quantum-statistical (density matrix) study of Bose-Einstein correlations (BEC's) is performed. The minimum number of independent parameters that enter into BEC's is determined. Expressions for the higher order correlation functions are derived, and the relation between BEC's and multiplicity distributions is clarified. New results concerning the interplay between the chaotic and the coherent component are presented. The investigation of the isospin dependence of BEC's leads to the prediction of quantum-statistical pi+pi- correlations and, related with it, the appearance of squeezed states in particle physics. Soft pions are found to play a specially important part in BEC's, both with respect to the experimental detection of the new correlation and in the clarification of the role of coherence. A significant increase of the available statistics in BEC's is necessary in order to test experimentally the new theoretical predictions. Two model sources are investigated: a ''static'' source and an expanding one. A comparison with a model proposed by Gyulassy, Kauffmann and Wilson is performed.