BUSKULIC, D (reprint author), CNRS,IN2P3,PHYS PARTICULES LAB,F-74019 ANNECY LE VIEUX,FRANCE.
Results on B0-BBAR0 mixing in e+e- annihilation at LEP are reported. A new method is used, where the charge of one b quark is tagged by a high-p, high-p(perpendicular-to) electron or muon, and the charge of the other is extracted from the momentum-weighted average of the charges of jet fragments. Based on the analysis of 180000 hadronic Z decays produced in the ALEPH detector, f(d-chi-d) + 0.72f(s-chi-s) = 0.113 +/- 0.018 (stat.) +/- 0.027 (syst.) is obtained. Combining this result with the ALEPH dilepton measurement yields chi = 0.129 +/- 0.022.