Probing parton distribution functions in massive lepton-pair production

We analyze massive $\mu$-pair production in hadron-hadron collisions using the parton model, and obtain expressions for general differential cross sections, $\frac{d\sigma }{d^{4}Q}$, in the $\mu$-pair momentum. We indicate ways in which the parton distributions in both longitudinal and transverse momenta may be probed in detail. Finally, we apply our results to the data by using parton distribution functions with threshold behavior ($\omega =\frac{1}{x}\to 1$) implied by the interchange model for large-angle scattering. Our results are that (1) the calculated cross section is only five percent of the observed cross section at Brookhaven energies; (2) inclusion of nonpointlike structure for the partons which enables one to explain the $e^{+}-e^{-}$ annihilation data results in only a marginal improvement in the normalization, but (perhaps accidentally) allows one to approximately describe the shape of the invariant mass distribution $\frac{d\sigma }{d{Q}^2}$.