Exclusive Processes at Intermediate Energy, Quark-hadron Duality and the Transition to Perturbative QCD.

Download or read book Exclusive Processes at Intermediate Energy, Quark-hadron Duality and the Transition to Perturbative QCD. written by and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Experiments at CEBAF will scan the intermediate-energy region of the QCD dynamics for the nucleon form factors and for Compton Scattering. These experiments will definitely clarify the role of resumed perturbation theory and of quark-hadron duality (QCD sum rules) in this regime. With this perspective in mind, the authors review the factorization theorem of perturbative QCD for exclusive processes at intermediate energy scales, which embodies the transverse degrees of freedom of a parton and the Sudakov resummation of the corresponding large logarithms. They concentrate on the pion and proton electromagnetic form factors and on pion Compton scattering. New ingredients, such as the evolution of the pion wave function and the complete two-loop expression of the Sudakov factor, are included. The sensitivity of their predictions to the infrared cutoff for the Sudakov evolution is discussed. They also elaborate on QCD sum rule methods for Compton Scattering, which provide an alternative description of th is process. They show that, by comparing the local duality analysis to resumed perturbation theory, it is possible to describe the transition of exclusive processes to perturbative QCD.