Observation of Λ0 b→ Λ+ c D(∗)0K− and Λ0 b→ Λ+ c D∗− s decays

Abstract

The decays Λ0 b → Λ+ c D(∗)0K − and Λ0 b → Λ+ c D∗− s are observed for the first time, in proton-proton collision data at √s = 13TeV, corresponding to an integrated luminosity of 5.4fb−1 collected with the LHCb detector. Their ratios of branching fractions with respect to the Λ0 b → Λ+ c D− s mode are measured to be B Λ0 b→ Λ+ c D0K − B Λ0 b→ Λ+ c D− s = 0.1908+0.0036 −0.0034 +0.0016 −0.0018 ± 0.0038, B Λ0 b→ Λ+ c D∗0K − B Λ0 b→ Λ+ c D− s = 0.589+0.018 −0.017 +0.017 −0.018 ± 0.012, B Λ0 b→ Λ+ c D∗− s B Λ0 b→ Λ+ c D− s = 1.668 ± 0.022+0.061 −0.055, where the first uncertainties are statistical, the second systematic, and the third, for the Λ0 b → Λ+ c D(∗)0K − decays, are due to the uncertainties on the branching fractions of the D− s → K −K +π− and D0 → K +π− decay modes. The measured branching fractions probe factorization assumptions in effective theories and provide the normalization for future pentaquark searches in Λ0 b → Λ+ c D(∗)0K − decay channels.