How to Analyze Lepton-Pair Production in Proton-Proton Collisions

We propose a systematic way to analyze lepton-pair production in proton-proton collisions, $p+p\to l^{+}+l^{-}+\mathrm{anything}$, in which the structure functions for the matrix element of the product of currents can be measured separately. It enables us to obtain additional information on the spin of constituents and to distinguish between the one-photon and two-photon processes. We also discuss briefly how to observe the $q$-number Schwinger terms and the short-distance behavior of the product of currents.