On angular correlation tests of QCD in semi-inclusive μp scattering

Abstract We calculate the effects on the azimuthal correlations predicted by QCD in semi-inclusive μp scattering due to the intrinsic transverse momentum k T of the struck parton and to the transverse momentum given to the hadron in the quark decay. We find that going to sufficiently large p T (⪆1.5 GeV/ c ) the smearing in azimuth due to the fragmentation process is practically eliminated, and the expected is about −0.10 to −0.20, depending on kinematical cuts. The effects of the intrinsic transverse momentum K T are discussed in some detail. Independently of the presence of K T effects and of the possible contamination from the naive parton model contribution, one can conclude that the lack of experimental observation of the expected effect at large p T would unambigously contradict the QCD expectation.