Observation of B -> K eta gamma

TL;DR

This paper reports the first observation of the radiative B decay to K eta gamma, measuring its branching fraction and setting limits on related decay modes, using data from the Belle detector at KEKB.

Contribution

First measurement of B -> K eta gamma decay and its branching fraction, expanding understanding of radiative B decays.

Findings

Observed B -> K eta gamma with a branching fraction of approximately 6.9 x 10^{-6}

Set an upper limit on B -> K3*(1780) gamma decay

Used 140 fb^{-1} data sample at the Upsilon(4S) resonance

Abstract

We report measurements of radiative B decays with K eta gamma final states, using a data sample of 140 /fb recorded at the Upsilon(4S) resonance with the Belle detector at the KEKB e+e- asymmetric energy collider. We observe B -> K eta gamma for the first time with a branching fraction of (6.9 +1.7-1.6 (stat) +1.3-1.0 (syst)) X 10^{-6} for M(Keta) < 2.4 GeV/c2. We also set an upper limit on B -> K3*(1780) gamma.