Measurement of Branching Fractions in Radiative B Decays to eta K gamma and Search for B Decays to eta' K gamma

TL;DR

This paper reports measurements of branching fractions for radiative B decays to eta and eta' K gamma final states, including charge asymmetry, using data from the BaBar detector, providing new experimental constraints on these rare decays.

Contribution

The study provides the first measurements and upper limits for B->eta' K gamma decays and detailed branching fractions for B->eta K gamma, enhancing understanding of radiative B decay processes.

Findings

Branching fraction for B0->eta K0 gamma: 11.3+2.8-2.6+/-0.6

Branching fraction for B+->eta K+ gamma: 10.0+/-1.3+/-0.5

Charge asymmetry in B+->eta K+ gamma: -0.09+/-0.12+/-0.01

Abstract

We present measurements of the B->eta K gamma branching fractions and upper limits for the B->eta' K gamma branching fractions. For B->eta K+ gamma we also measure the time-integrated charge asymmetry. The data sample, collected with the BaBar detector at the Stanford Linear Accelerator Center, represents 232 million produced B B-bar pairs. The results for branching fractions and upper limits at 90% C.L. in units of 10^{-6} are: Br(B0->eta K0 gamma)=11.3+2.8-2.6+/-0.6, Br(B+->eta K+gamma)=10.0+/-1.3+/-0.5, Br(B0->eta' K0 gamma)<6.6, Br(B+->eta' K+ gamma)<4.2. The charge asymmetry in the decay B+->eta K+ gamma is Ach =-0.09+/-0.12+/-0.01. The first errors are statistical and the second systematic.