Study of the fragmentation of b quarks into B mesons at the Z peak

A study of the fragmentation of b quarks into B mesons is presented. The analysis makes use of the statistics collected by the ALEPH experiment around the Z peak during the years 1991-1995. A semi- exclusive reconstruction of B to l nu D(*) decays is performed, by combining lepton candidates with fully reconstructed D(*) mesons, while the neutrino energy is estimated from the missing energy of the event. The mean reduced energy of the weakly decaying and leading B meson is found to be <x/sub b//sup wd/>=0.7198+or-0.0045(stat) +or-0.0053(syst) and <x/sub b//sup L/>=0.7394+or-0.0045(stat) +or-0.0053(syst) respectively. (4 refs).