Abstract:
We review the theory of hard exclusive scattering in Quantum Chromodynamics. After recalling the classical counting rules which describe the leading scale dependence of form factors and elastic reactions at fixed angle, the pedagogical example of the pion form factor is developped in some detail in order to show explicitely what factorization means in the QCD framework. The inclusion of transverse degrees of freedom leads to the discussion of Sudakov effects which are crucial for protecting the calculation from dangerous infrared regions. The picture generalizes to many hard reactions; a strategy to extract distribution amplitudes from future data is sketched. We discuss also the particular case of hadron-hadron collisions where the independent scattering mechanism dominates asymptotically and where a different factorization formula applies. We briefly present the concepts of color transparency and nuclear filtering and critically discuss the few present data on this subject.
Note:
  • to be published in the proceedings of the ELFE summer school on confinement physics, Cambridge (1995) ; no figures included
  • talk: Cambridge 1995/07/22
  • hard scattering: exclusive reaction
  • exclusive reaction: hard scattering
  • quantum chromodynamics
  • Compton scattering
  • electron pi: elastic scattering
  • elastic scattering: electron pi
  • pi: form factor
  • form factor: pi
  • space-time
Loading ...