Test of lepton universality using B⁺ →K⁺l⁺l^- decays

A measurement of the ratio of the branching fractions of the B+→K+μ+μ- and B+→K+e+e- decays is presented using proton-proton collision data, corresponding to an integrated luminosity of 3.0fb-1, recorded with the LHCb experiment at center-of-mass energies of 7 and 8 TeV. The value of the ratio of branching fractions for the dilepton invariant mass squared range 1<q2<6GeV2/c4 is measured to be 0.745-0.074+0.090(stat)±0.036(syst). This value is the most precise measurement of the ratio of branching fractions to date and is compatible with the standard model prediction within 2.6 standard deviations.