Speaker
Description
Generalized parton distributions (GPDs) encode important non-perturbative information of hadron structures including the tomographic parton images. We introduce a type of exclusive processes for a better study of GPDs, which we refer to as single diffractive hard exclusive processes (SDHEPs), and give a general argument for their factorization into GPDs. We advocate a two-stage framework for picturing SDHEPs, which not only gives a clear view of factorization properties but also provides a unified description of the kinematics including various polarization asymmetries. We demonstrate that the SDHEP is not only sufficiently generic to cover all known processes but also well motivated for searching for new processes for extracting GPDs. Importantly, we also examine the sensitivity of the SDHEP to the parton momentum fraction x-dependence of GPDs, and demonstrate it quantitatively with two specific processes that can be readily measured at J-PARC/AMBER using a pion beam and at JLab using a photon beam, respectively. Both processes are capable of providing enhanced sensitivity to the $x$-dependence, overcoming the problem of shadow GPDs, and disentangling different types of GPDs with various spin asymmetries.
