Observation of B+ -> proton Lambdabar gamma

TL;DR

This paper reports the first observation of the rare radiative hyperonic B decay B+ -> proton Lambdabar gamma, measuring its branching fraction and setting limits on related decay modes, advancing understanding of baryonic B decays.

Contribution

First observation and measurement of the branching fraction of B+ -> proton Lambdabar gamma decay using Belle data.

Findings

Branching fraction B(B+ -> proton Lambdabar gamma) = (2.16^{+0.58}_{-0.53} ext{(stat)} ext{+0.20}_{-0.20} ext{(sys)}) imes 10^{-6}

No significant signal for B+ -> proton Sigmabar gamma, upper limit set at 3.3 imes 10^{-6}

First measurement of this radiative hyperonic B decay

Abstract

We report the first observation of the radiative hyperonic B decay B+ -> proton Lambdabar gamma, using a 140 fb-1 data sample recorded on the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric energy e+e- collider. The measured branching fraction is B(B+ -> proton Lambdabar gamma) = (2.16 ^{+0.58}_{-0.53} +- 0.20) times 10^{-6}. A search for B+ -> proton Sigmabar gamma yields no significant signal, so we set a 90% confidence-level upper limit on the branching fraction of B(B+ -> proton Sigmabar gamma) < 3.3 times 10^{-6}.