First observation of a baryonic B+                      c decay

A baryonic decay of the B+ c meson, B+ c → J/ψpp¯π+, is observed for the first time, with a significance of 7.3 standard deviations, in pp collision data collected with the LHCb detector and corresponding to an integrated luminosity of 3.0 fb-1 taken at center-of-mass energies of 7 and 8 TeV. With the B+ c → J/ψπ+ decay as the normalization channel, the ratio of branching fractions is measured to be B(B+ c → J/ψpp¯π+)/B(B+ c → J/ψπ+) = 0.143+0.039 -0.034(stat) ± 0.013(syst). The mass of the B+ c meson is determined as M(B+ c) = 6274.0 ± 1.8(stat) ± 0.4(syst) MeV/c2, using the B+ c → J/ψpp¯π+ channel. © 2014 CERN, for the LHCb Collaboration.