Lawrence Berkeley National Laboratory

A search for the rare two-body charmless baryonic decay B+→pΛ¯$$ {B}^{+}\to p\overline{\varLambda} $$ 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+→pΛ¯$$ {B}^{+}\to p\overline{\varLambda} $$ 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+ → KS0π+ decay for normalisation, is ℬB+→pΛ¯=2.4−0.8+1.0±0.3×10−7,$$ \mathrm{\mathcal{B}}\left({B}^{+}\to p\overline{\varLambda}\right)=\left(2.{4}_{-0.8}^{+1.0}\pm 0.3\right)\times 1{0}^{-7}, $$ where the first uncertainty is statistical and the second systematic.