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

Abstract

This dissertation describes the measurement of the average B hadron lifetime using a high statistics sample of B {yields} J/{psi}X decays produced in p{bar p} collisions at a center of mass energy of {radical}s = 1.8 TeV at the Fermilab Tevatron. The integrated luminosity of the sample is 10.1 pb{sup -1} recorded with the Collider Detector at Fermilab (CDF). In this analysis the decay vertex of the decay J/{psi} {yields} {mu}{sup +}{mu}{sup -} 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/{psi} and their production cross sections. We find the following value for the average b hadron lifetime: {tau}{sub 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 {yields} J/{psi}X) {center_dot} BR(J/{psi} {yields} {mu}{sup +}{mu}{sup -}) = 7.7 x 10{sup -4}.