Studies of the decays B+ → p¯ph+ and observation of B+ → ¯Λ(1520)p

Abstract

Dynamics and direct C P violation in three-body charmless decays of charged B mesons to a proton, an antiproton and a light meson (pion or kaon) are studied using data, corresponding to an integrated luminosity of 1.0 fb − 1 , collected by the LHCb experiment in p p collisions at a center-of-mass energy of 7 TeV. Production spectra are determined as a function of Dalitz-plot and helicity variables. The forward-backward asymmetry of the light meson in the p ¯ p rest frame is measured. No significant C P asymmetry in B + → p ¯ p K + decay is found in any region of the Dalitz plane. We present the first observation of the decay B + → ¯¯¯ Λ ( 1520 ) ( → K + ¯ p ) p near the K + ¯ p threshold and measure B ( B + → ¯¯¯ Λ ( 1520 ) p ) = ( 3.9 + 1.0 − 0.9 ( stat ) ± 0.1 ( syst ) ± 0.3 ( BF ) ) × 10 − 7 , where BF denotes the uncertainty on secondary branching fractions.