Measurement of the CP asymmetry in B⁺→K⁺μ ⁺μ^- decays

A measurement of the CP asymmetry in B ⁺→K ⁺μ ⁺μ ^- decays is presented using pp collision data, corresponding to an integrated luminosity of 1.0 fb ^-1, recorded by the LHCb experiment during 2011 at a center-of-mass energy of 7 TeV. The measurement is performed in seven bins of μ ⁺μ ^- invariant mass squared in the range 0.05+→J/ψK ⁺ decay as a control mode. Averaged over all the bins, the CP asymmetry is found to be A _CP=0.000±0.033 (stat)±0.005 (syst)±0.007 (J/ψK), where the third uncertainty is due to the CP asymmetry of the control mode. This is consistent with the standard model prediction.