First observation of the decay B+ → π+ μ+ μ-

Abstract

A discovery of the rare decay B+ → π+ μ+ μ- is presented. This decay is observed for the first time, with 5.2 σ significance. The observation is made using pp collision data, corresponding to an integrated luminosity of 1.0 fb -1, collected with the LHCb detector. The measured branching fraction is (2.3 ± 0.6 (stat.) ± 0.1 (syst.))×10-8, and the ratio of the B+ → π+ μ+ μ- and B+ → K+ μ+ μ- branching fractions is measured to be 0.053 ± 0.014 (stat.) ± 0.001 (syst.). © 2012 CERN for the benefit of the LHCb collaboration.