Probing nonperturbative QCD through hadronic matrix elements extracted from exclusive hard processes
Abstract
QCD is the theory of strong interactions and nonperturbative methods have been developed to address the confinement property of QCD. Many experimental measurements probe the confining dynamics, and it is wellknown that hard scattering processes allow the extraction of non perturbative hadronic matrix elements. To study exclusive hard processes, such as electromagnetic form factors and reactions like gamma* N > gamma N', gamma* N > pi N', gamma* gamma > pi pi, antiproton proton >gamma* pi in particular kinematics (named as generalized Bjorken regime), one introduces specific nonperturbative objects, namely generalized parton distributions (GPDs), distribution amplitudes (DA) and transition distribution amplitudes (TDA), which are Fourier transformed nondiagonal matrix elements of nonlocal operators on the lightcone. We review here a selected sample of exclusive amplitudes in which the quark and gluon content of hadrons is probed, and emphasize that much remains to be done to successfully compute their nonperturbative parts. We present some difficulties with respect to the application of the much publicized AdSQCD approach to the calculation of these partonic quantities.
 Publication:

arXiv eprints
 Pub Date:
 September 2009
 DOI:
 10.48550/arXiv.0909.0098
 arXiv:
 arXiv:0909.0098
 Bibcode:
 2009arXiv0909.0098P
 Keywords:

 High Energy Physics  Phenomenology;
 High Energy Physics  Experiment;
 High Energy Physics  Lattice;
 Nuclear Theory
 EPrint:
 9 pages, proceedings of the Tenth Workshop on NonPerturbative Quantum Chromodynamics, Paris (France), June 812, 2009