Tests of quantum chromodynamics are proposed in the production of massive lepton pairs in hadronic collisions. Predictions are presented for the manner in which the transverse momentum distribution of the pair should change with changes in the mass and longitudinal momentum of the pair, and with changes in the overall energy of the collision. Data are shown to determine the average gluon momentum distribution in the nucleon. Lepton pair production in .pi. N and anti p N processes provides a method to isolate a gluon jet. 20 references.

A report is presented of recent experimental and theoretical progress in studies of the production of massive lepton pairs in hadronic collisions. Among the topics discussed are deviations from scaling, the status of the proofs of factorization in the parton model, higher-order terms in the QCD expansion, the discrepancy between measured and predicted yields (K factor), high-twist terms, soft gluon effects, and transverse momentum distributions.

We study the QCD evolution for the twist-three quark-gluon correlation functions associated with the transverse momentum odd quark distributions. Different from that for the leading twist quark distributions, these evolution equations involve more general twist-three functions beyond the correlation functions themselves. They provide important information on nucleon structure, and can be studied in the semi-inclusive hadron production in deep inelastic scattering and Drell-Yan lepton pair production in pp scattering process.

Inclusive distribution for lepton pair production was studied in QCD in an improved leading logarithms approximation that allows for large angle gluon correction. A formula is derived for arbitrary values of the dilepton transverse momentum. It does not factorize into the generalized Drell--Yan form. 10 references.

The hadroproduction of lepton pairs with mass Q and finite transverse momentum Q{sub T} is described in perturbative QCD by the same partonic subprocesses as prompt photon production. The authors demonstrate that, like prompt photon production, lepton pair production is dominated by quark-gluon scattering in the region Q{sub T}> Q/2. This feature leads to sensitivity to the gluon density in kinematical regimes accessible in collider and fixed target experiments, and it provides a new independent method for constraining the gluon density.