First evidence for the two-body charmless baryonic decay B[superscript 0] → p[line over p]

Abstract

The results of a search for the rare two-body charmless baryonic decays B[superscript 0]→p[line over p] and B[superscript 0][subscript s] →p[line over p] are reported. The analysis uses a data sample, corresponding to an integrated luminosity of 0.9 fb[superscript −1], of pp collision data collected by the LHCb experiment at a centre-of-mass energy of 7 TeV. An excess of B[superscript 0]→p[line over p] candidates with respect to background expectations is seen with a statistical significance of 3.3 standard deviations. This is the first evidence for a two-body charmless baryonic B[superscript 0] decay. No significant B[superscript 0][subscript s] → p[line over p] signal is observed, leading to an improvement of three orders of magnitude over previous bounds. If the excess events are interpreted as signal, the 68.3% confidence level intervals on the branching fractions are B(B[superscript 0] →p[line over p])=1.47[superscript +0.62+0.35][subscript −0.51−0.14] × 10[superscript −8], B(B[superscript 0]→p[line over p])=1.47[subscript −0.51−0.14][superscript +0.62+0.35] × 10[superscript −8], where the first uncertainty is statistical and the second is systematic.