Evidence for B to K eta' gamma Decays at Belle

TL;DR

This paper reports evidence for the B+ -> K+ eta' gamma decay with a measured partial branching fraction, and sets an upper limit for the B0 -> K0 eta' gamma decay, based on data from the Belle detector.

Contribution

First evidence for B+ -> K+ eta' gamma decay at 3.3 sigma, with a measured branching fraction, and an upper limit for B0 -> K0 eta' gamma, advancing understanding of radiative B decays.

Findings

Evidence for B+ -> K+ eta' gamma at 3.3 sigma

Measured partial branching fraction of (3.6 +/- 1.2 +/- 0.4) x 10^-6

Upper limit of 6.4 x 10^-6 for B0 -> K0 eta' gamma

Abstract

We present the results of a search for the radiative decay (B -> K eta' gamma) and find evidence for (B^+ -> K^+ eta' gamma) decays at the 3.3 standard deviation level with a partial branching fraction of (3.6 +/- 1.2 +/- 0.4) x 10e-6, where the first error is statistical and the second systematic. This measurement is restricted to the region of combined (K eta') invariant mass less than 3.4GeVc^2. A 90% confidence level upper limit of 6.4 x 10e-6 is obtained for the decay (B^0 -> K^0 eta' gamma) in the same (K eta') invariant mass region. These results are obtained from a 605 fb^-1 data sample containing 657 x 10e6 B anti-B pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^+e^- collider.