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 $B^+ \to K_S^O \pi^+$ decay for normalisation, is
$\mathcal{B}(B^+ \to p\overline{\Lambda}) = (2.4^{+1.0}_{−0.8} \pm 0.3) \times 10^{−7}$,
where the first uncertainty is statistical and the second systematic.
LHCb Collaboration