Ricerc@Sapienza

A measurement of the ratio of branching fractions of the decays B+→K+μ+μ-and B+→K+e+e-is presented. The proton-proton collision data used correspond to an integrated luminosity of 5.0 fb-1 recorded with the LHCb experiment at center-of-mass energies of 7, 8, and 13 TeV. For the dilepton mass-squared range 1.1<6.0 GeV2/c4 the ratio of branching fractions is measured to be RK=0.846-0.054+0.060-0.014+0.016, where the first uncertainty is statistical and the second systematic.

A search for the flavor-changing neutral-current decay ?c+?p?+?- is reported using a data set corresponding to an integrated luminosity of 3.0 fb-1 collected by the LHCb Collaboration. No significant signal is observed outside of the dimuon mass regions around the ? and ? resonances, and an upper limit is placed on the branching fraction of B(?c+?p?+?-)<7.7(9.6)×10-8 at 90%(95%) confidence level. A significant signal is observed in the ? dimuon mass region for the first time.