Study of the rare B[0 over s] and B[superscript 0] decays into the π[superscript +]π[superscript −]μ[superscript +]μ[superscript −] final state

Abstract

A search for the rare decays B[0 over s]→π[superscript +]π[superscript −]μ[superscript +]μ[superscript −] and B[superscript 0]→π[superscript +]π[superscript −]μ[superscript +]μ[superscript −] is performed in a data set corresponding to an integrated luminosity of 3.0 fb[superscript −1] collected by the LHCb detector in proton–proton collisions at centre-of-mass energies of 7 and 8 TeV. Decay candidates with pion pairs that have invariant mass in the range 0.5–1.3 [GeV over c superscript 2] and with muon pairs that do not originate from a resonance are considered. The first observation of the decay B[0 over s]→π[superscript +]π[superscript −]μ[superscript +]μ[superscript −] and the first evidence of the decay B[superscript 0]→π[superscript +]π[superscript −]μ[superscript +]μ[superscript −] are obtained and the branching fractions, restricted to the dipion-mass range considered, are measured to be B(B[0 over s]→π[superscript +]π[superscript −]μ[superscript +]μ[superscript −])=(8.6±1.5 (stat)±0.7 (syst)±0.7(norm))×10[superscript −8] and B(B[0 over s]→π[superscript +]π[superscript −]μ[superscript +]μ[superscript −])=(2.11±0.51(stat)±0.15(syst)±0.16(norm))×10[superscript −8], where the third uncertainty is due to the branching fraction of the decay B[superscript 0]→[J over ψ(→μ[superscript +]μ[superscript −])K*(892)[superscript 0](→K[superscript +]π[superscript −]), used as a normalisation.