B Meson Lifetimes , and B 0-B 0 Mixing Parameter ∆

We present a precise measurement of the standard model CP -violation parameter sin 2φ1, the direct CP violation parameter |λ|, the lifetimes of charged and neutral B mesons and their ratio, and the B0-B0 mixing parameter ∆md based on a sample of 152 × 10 6 BB pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. One of two B mesons is fully reconstructed in a CP -eigenstate or a flavor-eigenstate decay channel. The flavor of the accompanying B meson is identified from its decay products. From the distributions of the time interval between the two B meson decay points, we obtain sin 2φ1 = 0.728±0.056(stat) ± 0.023(syst), |λ| = 1.007 ± 0.041(stat) ± 0.033(syst), τB0 = [1.534 ± 0.008(stat) ± 0.010(syst)] ps, τB+ = [1.635 ± 0.011(stat) ± 0.011(syst)] ps, τB+/τB0 = 1.066 ± 0.008(stat) ± 0.008(syst) and ∆md = [0.511 ± 0.005(stat) ± 0.006(syst)] ps . The results for sin 2φ1 and |λ| are consistent with the standard model expectations. The significance of the observed deviation from unity in the lifetime ratio exceeds five standard deviations. PACS numbers: 11.30.Er, 12.15.Hh, 13.25.Hw ∗on leave from Nova Gorica Polytechnic, Nova Gorica