Rescattering in DIS and other QCD processes

Abstract

I discuss two issues related to interactions of partons moving in a color field. In deep inelastic scattering reinteractions of the struck quark in the color field of the target may neutralize the overall color exchange from the target. This allows the target to emerge with a rapidity gap to the rest of the produced hadrons: Diffractive DIS. In hard hadron-hadron interactions similar rescattering takes place, and again allows rapidity gap formation. Because of the different color environment in lepton vs. hadron induced processes the rescattering probabilities are not the same, hence the diffractive parton distributions are process-dependent. For both lepton and hadron induced diffraction the hard scattering subprocesses and their logarithmic scaling violations are, however, the same as in inclusive scattering. Another type of rescattering occurs when quarks and gluons move in the QCD vacuum condensate. Their long distance propagation is likely to be strongly affected by the condensate, which may explain why usual perturbation fails for soft processes. We have modelled the condensate by a ‘vacuum’ gluon field which carries zero four-momentum and couples to quarks and gluons in a gauge invariant way. The dressing of the free propagators by the vacuum gluons can be calculated exactly and shows that colored partons have a finite life-time. This framework may help address issues of analyticity and unitarity in theories where the fundamental fields differ from the asymptotic states of the S-matrix. PACS: 12.38.-t Quantum chromodynamics – 13.60.-r Photon and charged-lepton interactions with hadrons – 13.85.-t Hadron-induced high- and super-high-energy interactions