Structure functions and charge ratios in muon-nucleon scattering

We present the fractional energy distributions for positive and negative hadrons produced in muon-proton and muon-neutron scattering, and ensuing charge ratios for the photon fragmentation region. Data presented for a center-of-mass energy range $2.8<W<\mathrm{}4.5\mathrm{}$ GeV and a virtual-photon mass-squared range $0.5\le Q^2\le 4.5$ ${\mathrm{GeV}}^2$ indicate an overall equality of summed structure functions for neutron and proton targets, which exhibit approximate independence of $Q^2$ and ${\omega }^{\prime }$, Implications in terms of quark-fragmentation ideas are discussed.