Measurement of the branching fraction and CP asymmetry in B plus . J/.. plus decays

The branching fraction and direct CP asymmetry of the decay B +. J/.. + are measured using protonproton collision data collected with the LHCb detector at centre- of- mass energies of 7 and 8 TeV, corresponding to a total integrated luminosity of 3 fb - 1. The following results are obtained: ( B +. J/.. +) = ( 3.81 + 0.25 - 0.24 +/- 0.35) x 10 - 5, ACP ( B +. J/.. +) = - 0.045 + 0.056 - 0.057 +/- 0.008, where the first uncertainties are statistical and the second systematic. Both measurements are the most precise to date.