Observation of B+ to Lambda Lambdabar K+

TL;DR

This paper reports the first observation of the charmless hyperonic B decay B^+ --> Lambda Lambdabar K^+ with a measured branching fraction, and sets an upper limit for the related decay B^+ --> Lambda Lambdabar pi^+.

Contribution

First observation of B^+ --> Lambda Lambdabar K^+ decay and measurement of its branching fraction using Belle data.

Findings

Branching fraction B(B^+ --> Lambda Lambdabar K^+) = (2.91^{+0.90}_{-0.70} ext{(stat)} ext{+0.38}_{-0.38} ext{(syst)}) imes 10^{-6}

No significant signal for B^+ --> Lambda Lambdabar pi^+; upper limit set at 2.8 imes 10^{-6}.

First observation of this decay mode in charmless hyperonic B decays.

Abstract

We report the first observation of the charmless hyperonic B decay, B^+ --> Lambda Lambdabar K^+, using a 140 fb^-1 data sample recorded at the Upsilon(4S) resonance with the Belle detector at the KEKB e^+e^- collider. The measured branching fraction is B(B^+ --> Lambda Lambdabar K^+) = 2.91 ^{+0.90}_{-0.70} +/- 0.38 *10^-6 . We also perform a search for the related decay mode B^+ --> Lambda Lambdabar pi^+, but do not find a significant signal. We set a 90% confidence-level upper limit of B(B^+ --> Lambda Lambdabar pi^+) < 2.8 * 10^-6.