Observation of the decay Λb 0→Λc +pp‾π−

Abstract

The decay Λ0 b → Λ+ c p pπ − is observed using pp collision data collected with the LHCb detector at centre- of-mass energies of √s = 7 and 8 Tev, corresponding to an integrated luminosity of 3 fb−1. The ratio of branching fractions between Λ0 b → Λ+ c p pπ − and Λ0 b → Λ+ c π − decays is measured to be B(Λ0 b → Λ+ c p pπ −) B(Λ0 b → Λ+ c π −) = 0.0540 ± 0.0023 ± 0.0032. Two resonant structures are observed in the Λ+ c π − mass spectrum of the Λ0 b → Λ+ c p pπ − decays, corresponding to the Σc (2455)0 and Σ∗ c (2520)0 states. The ratios of branching fractions with respect to the decay Λ0 b → Λ+ c p pπ − are B(Λ0 b → Σ0 c p p) × B(Σ0 c → Λ+ c π −) B(Λ0 b → Λ+ c p pπ −) = 0.089 ± 0.015 ± 0.006, B(Λ0 b → Σ∗0 c p p) × B(Σ∗0 c → Λ+ c π −) B(Λ0 b → Λ+ c p pπ −) = 0.119 ± 0.020 ± 0.014. In all of the above results, the first uncertainty is statistical and the second is systematic. The phase space is also examined for the presence of dibaryon resonances. No evidence for such resonances is found.