Bose-Einstein correlations of pions in e/sup +/e/sup minus/ annihilation at 29 GeV center-of-mass energy

Abstract

Measurements of two-and three-particle correlations between like-sign pi ons produced in e + e~ annihilation at 29 GeV center-of-mass energy are pre sented. The analysis is based on data taken during the period 1982-1986 using the TPC/27 detector at PEP. Two-particle correlations are studied as a func tion of Q, the momentum difference as measured in the rest frame of the pion pair, and as a function of qo, the energy difference as measured in the lab frame. The Bose-Einstein enhancement is observed when Q is small even when the en ergy difference, 90, is substantial. This observation provides evidence that the Bose-Einstein correlations are best described by a model that correctly accounts for the relativistic motion of the particle sources. Three-pion correlations are measured both by using a standard three-pion correlation function, and also by using a correlation function for which the correlations between the pairs of pions within the triplet have been subtracted. The observation of three-pion corre lations after pair correlations have been subtracted supports the interpretation that the observed correlations are due to Bose-Einstein interference.