First observation of Λb0 → ςc (∗)++ D (∗)-K- decays

Abstract

The four decays, Λb0→ςc(∗)++D(∗)-K-, are observed for the first time using proton-proton collision data collected with the LHCb detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 6 fb-1. By considering the Λb0→Λc+D¯0K- decay as reference channel, the following branching fraction ratios are measured to be B(Λb0→ςc++D-K-)B(Λb0→Λc+D¯0K-)=0.282±0.016±0.016±0.005, B(Λb0→ςc∗++D-K-)B(Λb0→ςc++D-K-)=0.460±0.052±0.028, B(Λb0→ςc++D∗-K-)B(Λb0→ςc++D-K-)=2.261±0.202±0.129±0.046, B(Λb0→ςc∗++D∗-K-)B(Λb0→ςc++D-K-)=0.896±0.137±0.066±0.018, where the first uncertainties are statistical, the second are systematic, and the third are due to uncertainties in the branching fractions of intermediate particle decays. These initial observations mark the beginning of pentaquark searches in these modes, with more datasets to become available following the LHCb upgrade.