Hadronic B Decays to Charmless Final States and to J / ψK

Preliminary results from the BABAR experiment on charmless B decays to charged pions or kaons, and the measurement of the B→J/ψ K * decay amplitudes are presented. The data sample , collected at the asymmetric-energy B-factory PEP-II at SLAC, comprises a total number of 22.7 million Υ (4S) decays, corresponding to an integrated on-resonance luminosity of approximately 21 fb −1. We measure the following CP-averaged branching fractions: B(B 0 →π + π −) = (4.1 ± 1.0(stat) ± 0.7(sys)) × 10 −6 , B(B 0 →K + π −) = (16.7 ± 1.6(stat) +1.2 −1.7 (sys)) × 10 −6 , and an upper limit of B(B 0 →K + K −) < 2.5 × 10 −6 , at 90% confidence limit. The measurement of the J/ψK * decay amplitudes results in R ⊥ = 0.160 ± 0.032(stat) ± 0.036(sys), and reveals a dominant longitudinal component. The phase of the longitudinal amplitude shows evidence for non-vanishing final-state interaction.