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

Measurements of two and three particle correlations between sign pions produced in e+e- annihilation at 29 GeV center-o mass energy are presented. The analysis is based on data taken during the period 1982-1986 using the TPC/2γ detector at PEP. Two particle correlations are studied as a function of Q, the momentum difference as measured in the rest frame of the pion pair, and as a function of q0, the energy difference as measured in the lab frame. The Bose-Einstein enhancement is observed when Q is small even when the energy difference, q0, 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 correlations after pair correlations have been subtracted supports the interpretation that the observed correlations are due to Bose-Einstein interference