Search for Baryons in the Radiative Penguin Decay b--> s gamma

TL;DR

This study searched for baryon-involving radiative penguin B decays using CLEO data, found no evidence, and set upper limits on their branching fractions, constraining theoretical models and corrections to previous measurements.

Contribution

First to set experimental upper limits on baryonic radiative penguin B decays, refining constraints on theoretical predictions and previous measurements.

Findings

No evidence for the decays was observed.

Upper limits on branching fractions were established.

Constraints on corrections to previous measurements were derived.

Abstract

We have searched for the baryon-containing radiative penguin decays B^- -> \Lambda p-bar \gamma and B^- -> \Sigma^0 p-bar \gamma, using a sample of 9.7 million BBbar events collected at the \Upsilon(4S) with the CLEO detector. We find no evidence for either, and set 90% confidence level upper limits for photons with B rest frame energy greater than 2.0 GeV of [Br(B^- -> \Lambda p-bar \gamma) + 0.3 Br(B^- -> \Sigma^0 p-bar \gamma)] < 3.3 x 10^-6, [Br(B^- -> \Sigma^0 p-bar \gamma) + 0.4 Br(B^- -> \Lambda p-bar \gamma)] < 6.4 x 10^-6. From the latter, we estimate (for photons with B rest frame energy greater than 2.0 GeV) Br(B -> X_s \gamma, X_s containing baryons) < 3.8 x 10^-5. This limit implies upper limits on corrections to CLEO's recent measurement of branching fraction, mean photon energy, and variance in photon energy from b -> s \gamma that are less than half the combined statistical and systematic errors quoted on these quantities.