Measurement of CP asymmetries in the decays B⁰→ K^*0μ⁺μ⁻and B⁺→ K⁺μ⁺μ⁻

The direct CP asymmetries of the decays B⁰→ K^*0μ⁺μ⁻and B⁺→ K⁺μ⁺μ⁻are measured using pp collision data corresponding to an integrated luminosity of 3.0 fb⁻¹ collected with the LHCb detector. The respective control modes B⁰→ J/ψK^*0and B⁺→ J/ψK⁺are used to account for detection and production asymmetries. The measurements are made in several intervals of μ⁺μ⁻invariant mass squared, with the φ(1020) and charmonium resonance regions excluded. Under the hypothesis of zero CP asymmetry in the control modes, the average values of the asymmetries are A_CP (B⁰ → K^∗0µ⁺µ⁻) = −0.035 ± 0.024 ± 0.003, A_CP (B⁺ → K⁺µ⁺µ⁻) = 0.012 ± 0.017 ± 0.001, where the first uncertainties are statistical and the second are due to systematic effects. Both measurements are consistent with the Standard Model prediction of small CP asymmetry in these decays.