LargeP T photoproduction in the hard scattering expansion

Abstract

LargepT photoproduction is studied in the hard scattering expansion, including both three- and four-jet processes. The higher twist corrections (∝p T −6 andp T −8 ) to the basic QCD hard scattering process (∝p T −4 ) are estimated using the constituent interchange model and the various terms compared. Both single jet inclusive cross sections and single particle inclusive π0 cross sections are evaluated, the latter using scale violating fragmentation functions. We find that the higher twist terms are significant at present energies, particularly for three-jet events, though the four-jet anomalous photon contribution can be measured. Three-jet QCD processes require considerably higher energies to provide a significant contribution to the cross section. Methods of separating the different processes experimentally are discussed.