Semiexclusive Processes: A different way to probe hadron structure

TL;DR

This paper explores how semiexclusive processes, like high transverse momentum pion photoproduction, can be used to probe specific parton distributions and hadron structure, especially with polarized initial states.

Contribution

It introduces a method to use semiexclusive processes to access parton distributions, highlighting the potential of high-energy, hard processes to reveal detailed hadron structure information.

Findings

Perturbative processes dominate in certain regions, enabling parton structure probing.

Polarized initial states are essential for accessing polarization distributions.

Higher energy experiments can feasibly determine polarized gluon distributions.

Abstract

Hard semiexclusive processes provide an opportunity to design effective currents to probe specific parton distributions and to probe in leading order parton distributions that fully inclusive reactions probe only via higher order corrections. High transverse momentum pion photoproduction is an example of a such a process. We discuss the perturbative and soft processes that contribute, and show how regions where perturbative processes dominate can give us the parton structure information. Polarized initial states are needed to get information on polarization distributions. Current polarization asymmetry data is mostly in the soft region. However, with somewhat higher energy, determining the polarized gluon distribution using hard pion photoproduction appears quite feasible.