Direct Photons at the CERN ISR

摘要: A hard scatter between constituent partons in hadronic interactions usually results a system of two jets at large angles accompanied by spectator jets. The resulting high multiplicity and the variety contributing diagrams make comparison with theory difficult. However, processes where one out-going is replaced photon often offer more incisive experiment theory. Photons can be produced as result quark-gluon collisions (Compton process) or quark-antiquark annihilation. There are several higher order involving radiation photons from interacting quarks (bremsstrahlung will close to an accompanying jet. In proton-proton ISR energies, direct production predicted dominated Compton process. This implies that recoil (away-side) jet quark study thus fragmentation. Further, it would expected there no (same-side) jet, measurement cross section measure gluon structure function protons (modulo soft corrections).