@article{oai:tsukuba.repo.nii.ac.jp:00018226,
 author = {原, 和彦 and 金, 信弘 and CDF Collaboration and Hara, K. and Ikeda, H. and Kim, S. H.},
 issue = {11},
 journal = {Physical review D},
 month = {Nov},
 note = {We report the observation of bottom-charmed mesons Bc in 1.8 TeV pp- collisions using the CDF detector at the Fermilab Tevatron. The Bc mesons were found through their semileptonic decays, Bc±→J/ψl±X. A fit to the J/ψl mass distribution yielded 20.4-5.5+6.2 events from Bc mesons. A test of the null hypothesis, i.e., an attempt to fit the data with background alone, was rejected at the level of 4.8 standard deviations. By studying the quality of the fit as a function of the assumed Bc mass, we determined M(Bc)=6.40±0.39 (stat.)±0.13 (syst) GeV/c2. From the distribution of trilepton intersection points in the plane transverse to the beam direction we measured the Bc lifetime to be τ(Bc)=0.46-0.16+0.18 (stat)±0.03 (syst) ps. We also measured the ratio of production cross section times branching fraction for Bc+→J/ψl+ν relative to that for B+→J/ψK+ to be σ(Bc)×B(Bc→J/ψlν) / σ(B)×B(B→J/ψK)=0.132-0.037+0.041 (stat)±0.031 (syst)-0.020+0.032(lifetime).},
 title = {Observation of Bc mesons in pp- collisions at sqrt[s]=1.8 TeV},
 volume = {58},
 year = {1998}
}