A study of Bose-Einstein correlations in e+e- annihilations at LEP

Bose-Einstein correlations between like-sign charged track pairs have been studied in e+e- annihilation hadronic events at centre-of-mass energies around the Z0 peak as a function of Q, the four-momentum difference of the pair. The measurement was performed with the OPAL detector at LEP. Assuming the charged tracks to be pions, the observed Bose-Einstein enhancement was used to extract the values of the strength of the effect and the radius of the pion emitting source, which were found to be λ = 0.866 ± 0.032 ± 0.140 and R0 = 0.928 ± 0.019 ± 0.150 fm, respectively, where the first error is statistical and the second is systematic. The results do not show significant variation in comparison to e+e- annihilation measurements at lower centre-of-mass energies. If non-pion track contamination is taken into account, the value of the strength λ becomes consistent with unity. (orig.)