Simultaneous Measurement of the B0 Meson Lifetime and Mixing Frequency with B0 --> D*- 1+ nu Decays

Abstract

We measure the B{sup 0} lifetime {tau}{sub b{sup 0}} and the B{sup 0}-{bar B}{sup 0} oscillation frequency {Delta}m{sub d} with a sample of approximately 14,000 exclusively reconstructed B{sup 0} {yields} D*{sup -} {ell}{sup +} {nu}{sub {ell}} signal events, selected from 23 million B{bar B} pairs recorded at the {Upsilon}(4S) resonance with the BABAR detector at the Stanford Linear Accelerator Center. The decay position of the other B is determined with the remaining tracks in the event, and its b-quark flavor at the time of decay is determined with a tagging algorithm that exploits the correlation between the flavor of the b-quark and the charges of its decay products. The lifetime and oscillation frequency are measured simultaneously with an unbinned maximum-likelihood ({Delta}t) that uses, for each event, the measured difference in decay times of the two B mesons ({Delta}t), the calculated uncertainty on {Delta}t, the signal and background probabilities, and b-quark tagging information for the other B. The results are {tau}{sub B{sup 0}} = (1.523{sub -0.023}{sup +0.024} {+-} 0.022) ps and {Delta}m{sub d} = (0.492 {+-} 0.018 {+-} 0.013) ps{sup -1}.