Measurement of the average lifetime of hadrons containing bottom quarks

A measurement of the average lifetime of hadrons containing bottom quarks is presented. The b hadrons are produced in $e^{+}$ $e^{\mathrm{-}}$ annihilation at 29 GeV, and the lifetime is determined from the impact parameters of high-transverse-momentum electrons produced in the decay of the b hadrons. A b lifetime of ${\mathrm{\tau }}_{\mathit{b}}$=1.${17}_{\mathrm{-}0.22}^{+0.27\mathrm{}}$(stat${)}_{0.16}^{+0.17\mathrm{}}$(sys) psec is determined from a maximum-likelihood fit to the impact parameters. Particular care has been taken to describe the experimental resolution correctly in the fit.