Observation of B[superscript +][subscript c] → J=ψD(*) K(*) decays

Abstract

A search for the decays B[superscript +][subscript c] →J/ψD(*)[superscritp 0]K+ and B[superscript +][subscript c]→J/ψD(*)[superscript +]K[superscript *0] is performed with data collected at the LHCb experiment corresponding to an integrated luminosity of 3 fb[superscript -1]. The decays B[superscript +][subscript c]→J/ψD[superscript 0]K[superscript +] and B[superscript +][subscript c]→J/ψD[superscript ∗0]K][superscript +] are observed for the first time, while first evidence is reported for the B[superscript +][subscript c] →J/ψD[superscript ∗+]K[superscript ∗0] and B[superscript +][subscrip c]→J/ψD[superscript +]K[superscript ∗0] decays. The branching fractions of these decays are determined relative to the B[superscript +][subscript c]→J/ψπ[superscript +] decay. The B[superscript +][subscript c] mass is measured, using the J/ψD[superscript 0]K[superscript +] final state, to be 6274.28 ± 1.40(stat) ± 0.32(syst) MeV/c[superscript 2]. This is the most precise single measurement of the B[superscript +][subscript c] mass to date.