Measurement of the B0bar Lifetime and of the B0-B0bar Oscillation Frequency Using Partially Reconstructed B0bar -> D*+ l- anti-nu(l) Decays

We present a simultaneous measurement of the B0bar lifetime tau(B0) and mixing parameter $Delta m_d$. We use a sample of about 50000 B0bar -> D*+ l- anti-nu(l) partially reconstructed decays identified with the BABAR detector at the PEP-II storage ring at SLAC, where the flavor of the other B meson is determined from the charge of another high momentum lepton in the same event. The preliminary results are: tau(B0) = (1.501+/-0.008(stat.) +/- 0.030 (syst.)) ps, $Delta m_d$ = (0.523+/-0.004(stat.) +/- 0.007 (syst.)) ps^{-1}.