Rare B → baryon decays from CLEO

Abstract

We have searched for baryon-containing radiative penguin decays in 9.7 × 106 $B\bar{B}$ events collected at the Υ(4S) with the CLEO detector. We find no evidence for such decays, and set a 90% confidence level upper limit of ${\cal B} (B \rightarrow X_s \gamma, X_s ~{\it containing~baryons}) _{E_\gamma > 2.0 \rm{~GeV}} < 3.8 \times 10^{-5}$ . Corrections to CLEO’s recent b → s γ measurement due to $B \rightarrow X_s({\it baryon}) \gamma$ decays are well within the errors quoted. A search for semileptonic decays of B mesons to $e\bar{p}$ inclusive final states in the same data sample found no evidence for such decays and set an upper limit of ${\cal B} (B \rightarrow \bar{p} e^- \bar{\nu}_e X) < 5.9 \times 10^{-4}$ . These limits suggest that external W emission is not the dominant source of baryon production in B decay. PACS: 13.20.HeDecays of Bottom Mesons – 13.40.HqElectromagnetic Decays – 13.60.RjBaryon Production