THE DILEPTON-PRODUCTION CROSS-SECTION IN PRINCIPAL VALUE RESUMMATION

Using a recent calculation of the perturbative hard part for dilepton production that sums large threshold corrections to all orders in pert urbative QCD, we compute the corresponding cross sections, The hard pa rt has been evaluated using principal value resummation and contains a ll singular momentum-dependent corrections, We also include a resummat ion of large Sudakov terms, which are independent of parton momenta. W e give predictions for the dilepton-mass distribution, the rapidity di stribution and the rapidity-integrated K-factor at fixed-target energi es and compare with various experimental results in several kinematic regimes. We find that principal value resummation produces cross secti ons that are finite and well-behaved. For both protons and anti-proton s on fixed targets, the resummed cross sections are, in general, in ex cellent agreement with the data.