Observation of the decay B0s → ψ(2S) K+ π−

Abstract

The decay B-0s → ψ(2S)K+π- is observed using a data set corresponding to an integrated luminosity of 3.0fb-1 collected by the LHCb experiment in pp collisions at centre-of-mass energies of 7 and 8 TeV. The branching fraction relative to the B0 → ψ(2S)K+π- decay mode is measured to be, where fs/fd indicates the uncertainty due to the ratio of probabilities for a b quark to hadronise into a B0s or B0 meson. Using an amplitude analysis, the fraction of decays proceeding via an intermediate K*(892)0 meson is measured to be 0.645±0.049(stat)±0.049(syst) and its longitudinal polarisation fraction is 0.524±0.056(stat)±0.029(syst). The relative branching fraction for this component is determined to be. In addition, the mass splitting between the B0s and B0 mesons is measured as M(B0s)-M(B0)=87.45±0.44(stat)±0.09(syst)MeV/c2.