Detalle de: A precise measurement of the B + , B0 and mean b-hadron lifetime with the DELPHI detector at LEP I

Final results from the DELPHI Collaboration on the lifetime of B + and B0 mesons and the mean b-hadron lifetime, are presented using the data collected at the Z0 peak in 1994 and 1995. Elaborate, inclusive, secondary vertexing methods have been employed to ensure a b-hadron reconstruction with good efficiency. To separate samples of B + and B0 mesons, high performance neural network techniques are used that achieve very high purity signals. The results obtained are: $$ \tau_{\mathrm B}^ + = 1.624 \pm 0.014\;\;(stat) \pm 0.018\; (syst) ps $$$$ \tau_{\mathrm B}^0\quad = 1.531 \pm 0.021 \;\;(stat)\pm 0.031 \; (syst) ps $$$$ \frac{\tau_{{\mathrm B}^ + }}{\tau_{{\mathrm B}^0}} = 1.060 \pm 0.021 \;\;(stat)\pm 0.024\;(syst) $$ and for the average b-hadron lifetime: $$ \tau_{{\mathrm b}} = 1.570 \pm 0.005\;\;(stat) \pm 0.008 \; (syst) ps. $$