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: τB+=1.624±0.014(stat)±0.018(syst) ps, τB0=1.531±0.021(stat)±0.031(syst) ps, τB+/τB0=1.060±0.021(stat)±0.024(syst) and for the average b-hadron lifetime: τb=1.570±0.005(stat)±0.008 (syst) ps. (orig.)