| This thesis describes a measurement of the average proper decay time of the B+/-C mesons, the ground state of bottom and charm quark bound states. The lifetime measurement is carried out in the decay modes B+/-C → J/psi + e+/- + X and B+/-C → J/psi + mu+/- + X, where the J/psi decays as J/psi → mu +mu- and the X are unmeasured particles such as nue or numu. The data are collect by the CDF II detector which measures the properties of particles created in s = 1.96 TeV pp¯ collisions delivered by the Fermilab Tevatron. This measurement uses ∼ 1 fb-1 of integrated luminosity. The measured average proper decay time of B+/-C mesons, tau = 0.475+0.053-0.049 (stat.) +/- 0.018(syst.) ps, is competitive with the most precise measurements in the world and confirms previous measurements and theoretical predictions. |
