Measurement of the ratio of branching fractions and difference in CP asymmetries of the decays B ⁺ → J/ψπ ⁺ and B ⁺ → J/ψK ⁺

The ratio of branching fractions and the difference in CP asymmetries of the decays B⁺ → J/ψπ⁺ and B⁺ → J/ψK⁺ are measured using a data sample of pp collisions collected by the LHCb experiment, corresponding to an integrated luminosity of 3 fb⁻¹ at centre-of-mass energies of 7 and 8 TeV. The results are (Formula presented.) where the first uncertainties are statistical and the second are systematic. Combining this result with a recent LHCb measurement of A^{C P}(B⁺→ J/ ψK⁺) provides the most precise estimate to date of CP violation in the decay B⁺ → J/ψπ⁺, (Formula presented.).