High Transverse Momentum Meson Production: A Different Way To Probe Hadron Structure

TL;DR

This paper explores how high transverse momentum meson production, especially pion photoproduction, can be used to probe the parton structure of hadrons, emphasizing the role of perturbative processes and polarized states.

Contribution

It analyzes the interplay of perturbative and soft processes in high transverse momentum pion production and proposes using polarized initial states and upcoming machine capabilities to extract gluon polarization.

Findings

Perturbative processes can reveal parton structure regions.

Polarized initial states are essential for polarization distribution info.

EPIC machine could effectively determine polarized gluon distribution.

Abstract

Hard, or high transverse momentum, pion photoproduction can be a tool for probing the parton structure of the beam and target. 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 the proposed EPIC machine parameters, determining the polarized gluon distribution using hard pion photoproduction appears quite feasible.