$Q^2$-dependent parametrizations of parton distribution functions

We have used a large set of high-$Q^2$ data on deep-inelastic scattering, dimuon mass distributions, and $\frac{J}{\psi }$ $x_F$ distributions to extract estimates of the $Q^2$-dependent quark and gluon distribution functions in nucleons. The $Q^2$ dependence of these functions is parametrized in a manner convenient for predicting a large variety of reactions for $Q^2\simeq 4-200$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$ and for extrapolation to the ultrahigh values of $Q^2$ that will be probed by future accelerators in the TeV energy range.