A measurement of the average lifetime of B-hadrons produced bye+e−-collision at\(\left\langle {\sqrt s } \right\rangle = 36.3 GeV\)

Data taken with an improved tracking system have been used to determine the average lifetime of B-hadrons, τB. A study of the pseudo decay length gave $$\tau _B = (1.46 \pm 0.22(stat.) \pm 0.34(syst.)) ps$$ . From the impact parameter distribution of highp ⊥ electrons and muons, values of $$\tau _B = \left( {1.27_{ - 0.29}^{ + 0.35} \pm 0.17} \right) ps$$ and $$\tau _B = \left( {1.36_{ - 0.27}^{ + 0.32} \pm 0.14} \right) ps$$ were obtained. Combining these results, allowing for correlations and adding statistical and systematic errors in quadrature, we obtain $$\tau _B = \left( {1.36_{ - 0.23}^{ + 0.25} } \right) ps$$