Prompt electron production from the DELCO detector at the SLAC storage ring PEP

Abstract

We report final results on prompt electron production in hadronic events from $e^{+}$ $e^{\mathrm{-}}$ annihilations at √s =29 GeV, obtained with the DELCO detector at the SLAC storage ring PEP. We find the semielectronic branching ratios of charm and bottom quarks to be B(c→${\mathrm{se}}^{+}$ ${\nu }_e$ ${)=(11.6\mathrm{}}_{\mathrm{-}0.9}$ ${}_{}{}^{+1.1\mathrm{}}{}_{}{}^{}$)% and B(b→${\mathrm{ce}}^{\mathrm{-}}$ν${¯}_e$ ${)=(14.9\mathrm{}}_{\mathrm{-}1.9}$ ${}_{}{}^{+2.2\mathrm{}}{}_{}{}^{}$)% respectively. These results, from the complete data set, are consistent with an earlier analysis of partial data and indicate hard fragmentation functions for both c and b quarks, with mean values 〈$z_c$〉=0.59±0.04 and 〈$z_b$〉=0.72±0.05. The errors indicated here are a combination of statistical and systematic uncertainties.