Two-dimensional analysis of Bose-Einstein correlations in hadronic Z decays at LEP

Abstract

LAL 04-92Bose-Einstein correlations are studied in pairs of charged pions from hadronic Z decays, collected by the ALEPH detector.The correlation function, measured using either the unlike-sign or the mixed reference sample, is studied in terms of the Lorentz-invariant four-momentum difference and its transverse, $Q_{\textrm{T}}$, and longitudinal, $Q_{\textrm{L}}$, components with respect to the longitudinal centre-of-mass system. Values for the correlation radii, $R_{\textrm{T}}$ and $R_{\textrm{L}}$, are obtained from the fit of the Goldhaber parametrisation.The results indicate that the correlation radii values depend on the chosen kind of reference sample and on the two-jet purity