Observation of the $B_c$ meson in $p\bar{p}$ collisions at $\sqrt{s} = 1.8$ TeV

We have observed bottom-charm mesons B_c via the decay mode Bc -> J/psi lepton neutrino in 1.8 TeV p-bar p collisions using the CDF detector at the Fermilab Tevatron. A fit of background and signal contributions to the J/psi + lepton mass distribution yielded 20.4 +6.2 -5.5 events from B_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_c mass to be 6.40 +- 0.39 +- 0.13 GeVc^2 and the B_c lifetime to be tau(B_c) = 0.46 +0.18 -0.16 +- 0.03 ps. We measured the production cross section times branching ratio for B_c -> J/psi lepton neutrino relative to that for B+ -> J/psi K to be 0.132 +0.041 -0.037 (stat) +- 0.031 (syst) +0.032 -0.020 (lifetime).

Note:

13 pages, 3 figures. Submitted to Physical Review Letters. Available at http://www-cdf.fnal.gov/physics/pub98/cdf4496_Bc_PRL.ps Report-no: FERMILAB-PUB-98/157-E

anti-p p: colliding beams
anti-p p: inclusive reaction
B/c: hadroproduction
B/c: semileptonic decay
mass spectrum: (J/psi(3100) lepton)
B/c: mass
B/c: lifetime
channel cross section: branching ratio
CDF
experimental results

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