X-Dependence Of The Proton Structure Functions From Inelastic Antineutrino-Proton Scattering

From an analysis of 2275 $\overline{\ensuremath{\nu}}p\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}+{X}^{0}$ events at an average ${Q}^{2}$ of 4.5 Ge${\mathrm{V}}^{2}$, there are presented the first measurements, up to one undetermined overall normalization constant, of the $x$ dependence of the proton structure functions using antineutrinos, and of the $u$ and $\overline{d}+\overline{s}$ quark distributions. The result for $u(x)$ is in good agreement with models based on fits to electron and muon scattering data. With $u(x)$ normalized to those models the absolute antiquark momentum distribution $x[\overline{d}x+\overline{s}(x)]$ in the proton is determined.