Observation of the Bc meson in pp¯ collisions at √s = 1.8 TeV

We have observed bottom-charm mesons via the decay mode B{sub c}{sup {+-}}{yields}J/{psi}{ell}{sup {+-}}v in 1.8 TeV p{ovr p}collisions using the CDF detector at the Fermilab Tevatron. A fit of background and signal contributions to the J/{psi}{ell} mass distribution yielded 20.4{sub -5.5}{sup +6.2} events from B{sub c} mesons. A fit to the same distribution with background alone was rejected at the level of 4.8 standard deviations. We measured the B{sub c}{sup +} mass to be 6.40{+-}0.39(stat){+-}0.13(syst) GeV/c{sup 2} and the B{sub c}{sup +} lifetime to be 0.46{sub -0.16}{sup +0.18}(stat){+-}0.03(syst) ps. Our measured yield (production cross section times branching ratio) for B{sub c}{sup +}{yields}J/{psi}{ell}{sup +}v relative to that for B{sup +}{yields}J/{psi} K{sup +} is 0.132{sub -0.037}{sup +0.041}(stat){+-}0.031(syst){sub -0.020}{sup +0.032}(lifetime).