Evidence for the two-body charmless baryonic decay B+→pΛ¯

Abstract

A search for the rare two-body charmless baryonic decay $B^{+}\to p\overline{\Lambda }$ 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 $B^{+}\to p\overline{\Lambda }$ 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_S⁰π⁺ decay for normalisation, is $\mathrm{ℬ}\left(B^{+}\to p\overline{\Lambda }\right)=\left(2.4_{-0.8}^{+1.0}\pm 0.3\right)\times 10^{-7}\text{,}$ where the first uncertainty is statistical and the second systematic.