UC Irvine

Four data sets collected with the Mark II detector during its operation at the SPEAR and PEP e+e- storage rings at SLAC are used to study the Bose-Einstein correlation between pairs and triplets of like-sign charged pions. The data sets represent four different regions of energy available for hadron production: the J at s =3.095 GeV, typical hadronic energy of 5 GeV in two-photon events, and annihilation in the energy regions s =47 GeV above the J, and s =29 GeV. The Bose-Einstein correlation is studied as a function of Q2, the four-momentum difference squared of the pair, and of Q32, an analogous quantity defined for triplets. After corrections for Coulomb effects and pion misidentification, pair analyses indicate a nearly full Bose-Einstein enhancement (1) in the J and the two-photon data, and about half the maximum value in the two higher-energy data sets. The pair analysis parameter r lies within a band of ±0.1 fm around 0.7 fm and is essentially the same for all four data sets. Pion triplet analyses give consistent results for the triplet parameters 3 and r3. In an attempt to investigate the shape of the pion source, we also study the Bose-Einstein correlation in pion pairs using two-dimensional distributions in components of Q2. © 1989 The American Physical Society.