We have observed bottom-charm mesons via the decay mode B± c → J/ψl±ν in 1.8 TeV pp¯ collisions using the CDF detector at the Fermilab Tevatron. A fit of background and signal contributions to the J/ψl mass distribution yielded 20.4+6.2 -5.5 events from Bc mesons. A fit to the same distribution with background alone was rejected at the level of 4.8 standard deviations. We measured the B+ c mass to be 6.40 ± 0.39(stat) ± 0.13(syst) GeV/c2 and the B+ c lifetime to be 0.46+0.18 -0.16(stat) ± 0.03(syst)ps. Our measured yield (production cross section times branching ratio) for B± c → J/ψl+ν relative to that for B+ → J/ψK+ is 0.132+0.041 -0.037(stat) ± 0.031(syst)+0.032 -0.020(lifetime).
ASJC Scopus subject areas