Measurements of Bþ c Production and Mass with the Bþ c ! J=c þ Decay

Abstract

Measurements of B+c production and mass are performed with the decay mode B+c→J/ψπ+ using 0.37 fb−1 of data collected in pp collisions at √s=7 TeV by the LHCb experiment. The ratio of the production cross section times branching fraction between the B+c→J/ψπ+ and the B+→J/ψK+ decays is measured to be (0.68±0.10(stat)±0.03(syst)±0.05(lifetime))% for B+c and B+ mesons with transverse momenta pT>4 GeV/c and pseudorapidities 2.5<η<4.5. The B+c mass is directly measured to be 6273.7±1.3(stat)±1.6(syst) MeV/c2, and the measured mass difference with respect to the B+ meson is M(B+c)−M(B+)=994.6±1.3(stat)±0.6(syst) MeV/c2.