Measurement of the Inclusive B-Lifetime Using $\rm {J/\psi}$'s at the CDF Experiment

This dissertation describes the measurement of the average B hadron lifetime using a high statistics sample of B → J/ΨX decays produced in p$\bar{p}$ collisions at a center of mass energy of √s = 1.8 TeV at the Fermilab Tevatron. The integrated luminosity of the sample is 10.1 pb^-1 recorded with the Collider Detector at Fermilab (CDF). In this analysis the decay vertex of the decay J/Ψ → μ⁺μ^- as reconstructed by a silicon vertex detector is used to extract the lifetime from the data. This measurement is the average over all b-hadrons produced weighted by the product of their branching ratios into J/Ψ and their production cross sections. We find the following value for the average b hadron lifetime: τ_B = 1.46 ± 0.06(stat.) ± 0.06(syst.) ps. This is the first measurement of the b-hadron lifetime at a hadron collider. It demonstrates that it is possible to access the large b-quark production cross section in p$\bar{p}$ collisions and to achieve high statistics even in modes which have small product branching ratios as in this case: BR(B → J/ΨX) • BR(J/Ψ → μ⁺μ^-) = 7.7 x 10<sup>-4