Measurement of the branching fraction ratio B (Bc+ →ψ (2S)π+) / B (Bc+ →j /ψπ+)

Using pp collision data collected by LHCb at center-of-mass energies s=7TeV and 8 TeV, corresponding to an integrated luminosity of 3fb-1, the ratio of the branching fraction of the Bc+→ψ(2S)π+ decay relative to that of the Bc+→J/ψπ+ decay is measured to be 0.268±0.032(stat)±0.007(syst)±0.006(BF). The first uncertainty is statistical, the second is systematic, and the third is due to the uncertainties on the branching fractions of the J/ψ→μ+μ- and ψ(2S)→μ+μ- decays. This measurement is consistent with the previous LHCb result, and the statistical uncertainty is halved.