Measurement of Branching Fraction and CP Asymmetry in B-> eta h Decays

Abstract

We report measurements of $B$ to pseudoscalar-pseudoscalar decays with at least one eta meson in the final state using 140 fb^{-1} of data collected by the Belle detector at KEKB e^+ e^- collider. We observe the decays of B^+-> eta pi^+ and B^+-> eta K^+; the measured branching fractions are Br(B^+-> eta pi^+) = (4.8^{+0.8}_{-0.7}(stat) +- 0.3 (sys)) * 10^-6 and Br(B^+-> eta K^+) = (2.1 +- 0.6 (stat) +- 0.2 (sys)) * 10^-6. Their corresponding CP violating asymmetries are measured to be 0.07 +- 0.15 +- 0.03 for eta pi^+- and -0.49 +- 0.31 +- 0.07 for eta K^+-. No significant signals are found for neutral B meson decays. We report the following upper limits on branching fractions at the 90% confidence level: Br(B^0 -> eta K^0) < 2.0 * 10^-6, Br(B^0-> eta pi^0) < 2.5 * 10^-6 and Br(B^0 -> eta eta) < 2.0 * 10^-6.