Measurement of Bose-Einstein correlations at LEP

A review of Bose-Einstein correlations is presented here using data collected at LEP. Bose-Einstein correlations have been studied in hadronic Z decays produced in e+e- interactions at √s ∼ 91 GeV. They have been observed in pairs of identical pions, charged and neutral, showing a smaller size for the neutral source. Also a multidimensional analysis has been performed that shows an elongation of the source along the direction of the motion of the original quark. At higher centre of mass energies, (√s ∼ 200 GeV), it was possible to study the Bose-Einstein effect in W-pair production. In particular, Bose-Einstein correlations are investigated between particles coming from different W's as they may influence the W mass measurement in the four-jet channel