Observation of the decay Λ0b → χc1pπ−

Abstract

The Cabibbo-suppressed decay Λ0b → χc1pπ− is observed for the first time using data from proton-proton collisions corresponding to an integrated luminosity of 6 fb−1, collected with the LHCb detector at a centre-of-mass energy of 13 TeV. Evidence for the Λ0b → χc2pπ− decay is also found. Using the Λ0b → χc1pK− decay as normalisation channel, the ratios of branching fractions are measured to be: B(Λ0b→χc1pπ−)B(Λ0b→χc1pK−)= 6.59±1.01±0.22)×10−2 B(Λ0b→χc2pπ−)B(Λ0b→χc1pπ−)= 0.95±0.30±0.04±0.04 B(Λ0b→χc2pK−)B(Λ0b→χc1pK−)= 1.06±0.05±0.04±0.04, where the first uncertainty is statistical, the second is systematic and the third is due to the uncertainties in the branching fractions of χc1,2 → J/ψγ decays.