If $\sigma(\bar{v}) / \sigma(v)=R$, show that
$$
\frac{\int x \bar{Q}(x) d x}{\int x Q(x) d x}=\frac{3 R-1}{3-R} .
$$
Detailed analyses show that the functions $u(x), d(x), \ldots$, are indeed the same whether one extracts them from electroproduction or neutrino experiments. This is a definitive success of the parton model: the $u(x), d(x)$, describe the intrinsic structure of the hadronic target and are the same whatever experimental probe is used to determine them.