Observation of the decay Bc+→ψ(2S)π+

Abstract

The decay B + c → ψ ( 2 S ) π + with ψ ( 2 S ) → μ + μ − is observed with a significance of 5.2 σ using p p collision data corresponding to an integrated luminosity of 1.0 fb − 1 collected by the LHCb experiment. The branching fraction of B + c → ψ ( 2 S ) π + decays relative to that of the B + c → J / ψ π + mode is measured to be B ( B + c → ψ ( 2 S ) π + ) B ( B + c → J / ψ π + ) = 0.250 ± 0.068 ( stat ) ± 0.014 ( syst ) ± 0.006 ( B ) . The last term is the uncertainty on the ratio B ( ψ ( 2 S ) → μ + μ − ) / B ( J / ψ → μ + μ − ).