Transverse momenta of partons and dimuons in QCD

Intrinsic (primordial) transverse momenta of quarks and gluons are calculated as well as those arising from recoil (bremsstrahlung) effects, using only the well-known parton distributions as input. The intrinsic k/sub T/s lie typically in the range of 150-250 MeV. Recent approaches using heuristic integro-differential equations for k/sub T/ distributions of partons are shown to disagree with the results obtained by rigorous QCD calculations. The transverse momenta of dimuon pairs produced in pp to mu /sup +/ mu /sup -/+X at the ISR can be solely explained by dynamical recoil effects, i.e. qq to ( mu /sup +/ mu /sup -/)g and gq to ( mu /sup +/ mu /sup -/)q, and no significant intrinsic transverse parton momenta are required. These dimuon transverse momenta show a pronounced energy dependence which could be easily tested at the CERN ISR. (34 refs)