Exclusive processes at JLab at 6 GeV

University of Connecticut

^a e-mail: kenjo@jlab.org

Published online: 23 January 2015

Abstract

Deeply virtual exclusive reactions provide a unique opportunity to probe the complex internal structure of the nucleon. They allow to access information about the correlations between parton transverse spatial and longitudinal momentum distributions from experimental observables. Dedicated experiments to study Deeply Virtual Compton Scattering (DVCS) and Deeply Virtual Meson Production (DVMP) have been carried out at Jefferson Lab using continuous electron beam with energies up to 6 GeV. Unpolarized cross sections, beam, target and double spin asymmetries have been measured for DVCS as well as for π⁰ exclusive electroproduction. The data from Hall B provide a wide kinematic coverage with Q²=1-4.5 GeV², x_B=0.1-0.5, and −t up to 2 GeV₂. Hall A data have limited kinematic range partially overlapping with Hall B kinematics but provide a high accuracy measurements. Scaling tests of the DVCS cross sections provide solid evidence of twist-2 dominance, which makes chiral-even GPDs accessible even at modest Q². We will discuss the interpretation of these data in terms of Generalized Parton Distributions (GPDs) model. Successful description of the recent CLAS π⁰ exclusive production data within the framework of the GPD-based model provides a unique opportunity to access the chiral-odd GPDs.