Search for the Bc meson in hadronic Z0 decays

A search for decays of the B-c meson was performed using data collected from 1990-1995 with the OPAL detector on or near the Z(o) peak at LEP. The decay channels B-c(+) --> J/psi pi(+), B-c(+) --> J/psi a(1)(+) and B-c(+) --> J/psi l(+) nu were investigated, where l denotes an electron or a muon. Two candidates are observed in the mode B-c(+) --> J/psi pi(+), With an estimated background of (0.63 +/- 0.20) events. The weighted mean of the masses of the two candidates is (6.32 +/- 0.06) GeV/c(2), which is consistent with the predicted mass of the B-c meson. One candidate event is observed in the mode B-c(+) --> J/psi l(+) nu, with an estimated background of (0.82 +/- 0.19) events. No candidate events are observed in the B-c(+) --> J/psi a(1)(+) decay mode, with an estimated background of (1.10 +/- 0.22) events, Upper bounds at the 90% confidence level ate set on the production rates for these processes. (C) 1998 Published bq Elsevier Science B.V.