Measurements of the S-wave fraction in B 0 → K + π − μ + μ − decays and the B 0 → K ∗(892)0 μ + μ − differential branching fraction

Abstract

A measurement of the differential branching fraction of the decay B 0 K * (892) 0 + -is presented together with a determination of the S-wave fraction of the K + -system in the decay B 0 K + - + -. The analysis is based on ppcollision data corresponding to an integrated luminosity of 3 fb -1 collected with the LHCb experiment. The measurements are made in bins of the invariant mass squared of the dimuon system, q 2 . Precise theoretical predictions for the differential branching fraction of B 0 K * (892) 0 + -decays are available for the q 2 region 1.1 < q 2 < 6.0 GeV 2 /c 4 . In this q 2 region, for the K + -invariant mass range 796 < m K < 996 MeV/c 2 , the S-wave fraction of the K + -system in B 0 K + - + -decays is found to be F S = 0.101 0.017(stat) 0.009(syst), and the differential branching fraction of B 0 K * (892) 0 + -decays is determined to be dB/dq 2 = (0.392 +0.020 -0.019 (stat) 0.010(syst) 0.027(norm)) 10 -7 c 4 /GeV 2 .