Further studies on Bose-Einstein correlations in W-pair decays

Bose-Einstein correlations in W-pair decays are studied using data collected by the ALEPH detector at centre-of-mass energies up to 208 GeV. The analysis presented is based on the comparison of selected $WW \rightarrow q \bar{q}q \bar{q}$ events to "mixed" events constructed from the hadronic parts of selected $WW \rightarrow q \bar{q} \ell \nu$ events using the $\Delta \rho$ distribution. The data distribution is consistent with $\Delta \rho = 0$ predicted when the Bose-Einstein correlations are present only for pions coming from the same W. The JETSET model with the Bose-Einstein correlations between pions from di erent W's is disfavoured.