BUSKULIC, D (reprint author), CNRS, IN2P3, PHYS PARTICULES LAB, F-74019 ANNECY LE VIEUX, FRANCE.
The time dependence of B(d)0-B(d)0BAR oscillations has been observed using events with a D*, decaying into a D0pi+, and a lepton in opposite hemispheres. The time dependence of the oscillations is derived from the displacement of the D0 vertex and the D*-lepton charge correlation. From a fit for the oscillation frequency the mass difference of the B(d)0 states is measured: DELTAm = [3.44(-0.70)+0.65(stat.)-0.20(+0.26)(syst.)] x 10(-4) eV/c2.