Study of the B+→J/ψΛ¯p decay in proton-proton collisions at √s = 8 TeV

Abstract

A study of the B+ → J/ψΛp decay using proton-proton collision data collected at √s = 8 TeV by the CMS experiment at the LHC, corresponding to an integrated luminosity of 19.6 fb−1 , is presented. The ratio of branching fractions B(B+ → J/ψΛp)/B(B+ → J/ψK ∗ (892)+ ) is measured to be (1.054 ± 0.057(stat) ± 0.035(syst) ± 0.011(B))%, where the last uncertainty reflects the uncertainties in the world-average branching fractions of Λ and K∗ (892)+ decays to reconstructed final states. The invariant mass distributions of the J/ψΛ, J/ψp, and Λp systems produced in the B+ → J/ψΛp decay are investigated and found to be inconsistent with the pure phase space hypothesis. The analysis is extended by using a model-independent angular amplitude analysis, which shows that the observed invariant mass distributions are consistent with the contributions from excited kaons decaying to the Λp system.