Measurements of branching fractions in B -> phi K and B -> phi pi and search for direct CP violation in B+/- -> phi K+/-

TL;DR

This paper reports precise measurements of branching fractions for B meson decays involving phi and K particles, and searches for direct CP violation, using a large data sample from the BaBar experiment.

Contribution

First measurement of branching fractions for B+ and B0 decays to phi K, and the first search for direct CP violation in B+/- to phi K+/- decays.

Findings

Branching fraction B(B+ --> phi K+) = (10.0 +0.9 -0.8 +/- 0.5) x 10^{-6}

Branching fraction B(B0 --> phi K0) = (8.4 +1.5 -1.3 +/- 0.5) x 10^{-6}

CP asymmetry ACP = 0.04 +/- 0.09 +/- 0.01

Abstract

We present measurements of branching fractions in the b -> s s-bar s penguin-dominated decays B+ --> phi K+ and B0 --> phi K0 in a sample of approximately 89 million BBbar pairs collected by the BaBar detector at the PEP-II asymmetric-energy B-meson factory at SLAC. We determine B(B+ --> phi K+) = (10.0 +0.9 -0.8 +/- 0.5) x 10^{-6} and B(B0 --> phi K0) = (8.4 +1.5 -1.3 +/- 0.5) x 10^{-6}. Additionally, we measure the CP-violating charge asymmetry ACP (B+/- --> phi K+/-) = 0.04 +/- 0.09 +/- 0.01, with a 90% confidence interval of [-0.10, 0.18], and set an upper limit B(B+ --> phi pi+) < 0.41 x 10^{-6} (at the 90% confidence level).