Measurement of the Oscillation Frequency for B0-Bobar Mixing using   Hadronic B0 Decays
  The oscillation frequency of B0-B0bar mixing (Delta-m_d) has been measured using 29.1 fb^{-1} of datacollected with the Belle detector at KEKB. This measurement is made through the distributions of the proper decay time difference of B pairs in events tagged as same- and opposite-flavor decays. In each event, one $B$ is fully reconstructed in a flavor-specific hadronic decay mode, while the flavor of the other is extracted through a likelihood calculated from the b-flavor information carried in its final decay products. We obtain Delta-m_d = (0.528 +- 0.017 +- 0.011) ps^{-1}, where the first error is statistical and the second error is systematic. 
Belle Collaboration, T.Tomura, et al