Measurement of the Bc± Meson Lifetime Using Bc± → J/ψ + l± + X Decays

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