Observation of the decay B(c)(+/-) -> J/psi pi(+/-) and measurement of the B(c)(+/-) mass

The B(c)(+/-) meson is observed through the decay B(c)(+/-) -> J/psi pi(+/-), in data corresponding to an integrated luminosity of 2.4 fb(-1) recorded by the Collider Detector at Fermilab II detector at the Fermilab Tevatron. A signal of 108 +/- 15 candidates is observed, with a significance that exceeds 8 sigma. The mass of the B(c)(+/-) meson is measured to be 6275.6 +/- 2.9(stat) +/- 2.5(syst) MeV/c(2).