Quark-Parton Model Predictions for Hadronic Charge Ratios in Inclusive Lepton-Induced Reactions

Abstract

We investigate the predictions of the quark-parton model for hadronic charge ratios in the current-fragmentation region in inclusive lepton-induced reactions. We use parton distribution functions given by McElhaney and Tuan from fits to single-arm inelastic electron scattering data, and we obtain relative parton fragmentation functions from a fit to the $\frac{{\ensuremath{\pi}}^{+}}{{\ensuremath{\pi}}^{\ensuremath{-}}}$ ratio in electroproduction from a proton target. The electroproduced $\frac{{\ensuremath{\pi}}^{+}}{{\ensuremath{\pi}}^{\ensuremath{-}}}$ ratio from a neutron target is predicted to be \ensuremath{\gtrsim} 1.2 at moderate $\ensuremath{\omega}$ and 1 at small $\ensuremath{\omega}$, providing a dramatic test of the model. The model gives a neutrino-(antineutrino-) produced $\frac{{\ensuremath{\pi}}^{+}}{{\ensuremath{\pi}}^{\ensuremath{-}}}$ ($\frac{{\ensuremath{\pi}}^{\ensuremath{-}}}{{\ensuremath{\pi}}^{+}}$) ratio of 3.0 \ifmmode\pm\else\textpm\fi{} 0.6 from any target. Also the ratio of charged to neutral $K$ production in ${e}^{+}{e}^{\ensuremath{-}}$ annihilation should be 1.38 \ifmmode\pm\else\textpm\fi{} 0.10.