A Measurement of B+ and B0 lifetimes using Dˉℓ+ events

Abreu, P. [--] Cortina Gil, Eduardo [UCL] DELPHI Collaboration [--] et al.

A measurement of B meson lifetimes is presented using data collected from 1991 to 1993 by the DELPHI detector at the LEP collider. Samples of events with a D meson and a lepton in the same jet are selected where D~ + and D*-g + events originate mainly from the semileptonic decays of B + and B ~ mesons, respectively. From the reconstructed B decay length and the estimated B momentum, taking into account the dilution due to B decays into D**(+u, the following B meson lifetimes and lifetime ratio are measured: ~-(B +) = 1.61+_~ (stat.) 4- 0.12 (syst.) ps ~-(B ~ = 1.61+_oo!43 (stat.) • 0.08 (syst.) ps ~-(B+)/~-(B ~ = 1.00+_o6!~v5 (stat.) • 0.10 (syst.) and an average lifetime of B + and B ~ mesons is obtained: ~-(B) = 1.61+~176 (stat.)• 0.05 (syst.) ps