Prompt muon production ine+e−annihilations at 29 GeV

We have studied the production of prompt muons in hadronic events from ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$ annihilation at a center-of-mass energy of 29 GeV with the PEP4-TPC (Time Projection Chamber) detector. The muon p and ${p}_{t}$ distributions are well described by a combination of bottom- and charm-quark decays, with fitted semimuonic branching fractions of (15.2\ifmmode\pm\else\textpm\fi{}1.9\ifmmode\pm\else\textpm\fi{}1.2)% and (6.9\ifmmode\pm\else\textpm\fi{}1.1\ifmmode\pm\else\textpm\fi{}1.1)%, respectively. The muon spectra imply hard fragmentation functions for both b and c quarks, with 〈z(b quark)〉=0.80\ifmmode\pm\else\textpm\fi{}0.05\ifmmode\pm\else\textpm\fi{}0.05 and 〈z(c quark)〉=0.60\ifmmode\pm\else\textpm\fi{}0.06\ifmmode\pm\else\textpm\fi{}0.04. We derive neutral-current axial-vector couplings of a(b quark)=-0.9\ifmmode\pm\else\textpm\fi{}1.1\ifmmode\pm\else\textpm\fi{}0.3 and a(c quark)=1.5\ifmmode\pm\else\textpm\fi{}1.5\ifmmode\pm\else\textpm\fi{}0.5 from the forward-backward asymmetries.