Evidence for the two-body charmless baryonic decay ${B}^{+}\to p\overline{\varLambda}$

Abstract

A search for the rare two-body charmless baryonic decay ${B}^{+}\to p\overline{\varLambda}$ is performed with pp collision data, corresponding to an integrated luminosity of 3 fb⁻¹, collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. An excess of ${B}^{+}\to p\overline{\varLambda}$ candidates with respect to background expectations is seen with a statistical significance of 4.1 standard deviations, and constitutes the first evidence for this decay. The branching fraction, measured using the B ⁺ → K ⁰_S π ⁺ decay for normalisation, is

$$ \mathrm{\mathcal{B}}\left({B}^{+}\to p\overline{\varLambda}\right)=\left(2.{4}_{-0.8}^{+1.0}\pm 0.3\right)\times 1{0}^{-7}, $$

where the first uncertainty is statistical and the second systematic.