Improved Measurements of Branching Fractions and CP Asymmetries in B-> eta h Decays

TL;DR

This paper presents improved measurements of B meson decays involving eta mesons, including branching fractions and CP asymmetries, using Belle detector data, providing more precise insights into these decay processes.

Contribution

The study provides the first precise measurements of specific B->eta h decay branching fractions and CP asymmetries, enhancing understanding of CP violation in these channels.

Findings

Measured branching fractions for B+ -> eta pi+ and B+ -> eta K+ decays.

Observed CP asymmetries in eta pi+ and eta K+ decay modes.

Set an upper limit for B0 -> eta K0 decay at 1.9x10^{-6}.

Abstract

We report improved measurements of B decays with an eta meson in the final state using 492 fb^{-1} of data collected by the Belle detector at the KEKB e^+ e^- collider. We observe the decays B^{+-}-> eta pi^{+-} and B^{+-}-> eta K^{+-}; the measured branching fractions are Br(B^{+-}-> eta pi^{+-}) = (4.2+- 0.4(stat)+- 0.2(sys))x10^{-6} and Br(B^{+-}-> eta K^{+-}) = (1.9+-0.3(stat)^{+0.2}_{-0.1}(sys))x10^{-6}. The corresponding CP-violating asymmetries are measured to be -0.23+- 0.09(stat) +-0.02(sys) for eta pi^{+-} and -0.39+-0.16(stat)+-0.03(sys) for eta K^{+-}. We also search for B^0-> eta K^0 decays and set an upper limit of 1.9x10^{-6} at the 90% confidence level.