UC Berkeley

We present measurements of branching fractions in the b→ss̄s penguin-dominated decays B+→φK+ and B 0φK0 in a sample of approximately 89 million BB̄ pairs collected by the BABAR detector at the PEP-II asymmetric-energy B-meson factory at SLAC. We determine B(B+→φK+) = (10.0-08+09±0.5)×10-6 and B(B 0→φK0) = (8.4-13+15± 0.5)×10-6. Additionally, we measure the CP-violating charge asymmetry ACP(B±→φK±) = 0.04±0.09±0.01, with a 90% confidence-level interval of [-0.10,0.18], and set an upper limit on the CKM- and color-suppressed decay B+→φπ+, B(B+→φπ +)<0.41× 10-6 (at the 90% confidence level). © 2004 The American Physical Society.