LHCb CollaborationAlfonso Albero, AlejandroComerma Montells, AlbertGarcia Moreno, PaulaGarrido Beltrán, LluísGioventù, AlessandraGironella Gironell, PereGomez Fernandez, SergioGraugés Pous, EugeniLobo Salvia, AniolLópez Huertas, AlbertManera Escalero, RafelMarin Benito, CarlaMauricio Ferre, JoanVazquez Gomez, Ricardo2025-06-062025-06-062024-06-051434-6044https://hdl.handle.net/2445/221417The 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.18 p.application/pdfengcc-by (c) LHCb Collaboration et al., 2024http://creativecommons.org/licenses/by/4.0/Física de partículesQuarksParticle physicsQuarksinfo:eu-repo/semantics/article7564622025-06-06info:eu-repo/semantics/openAccess