Exclusive $\pi^+$ electroproduction off the proton from low to high -t

TL;DR

This study measures exclusive $^+$ meson electroproduction cross sections over a range of momentum transfer -t to explore the transition from non-perturbative to perturbative QCD regimes, providing insights into hadronic structure.

Contribution

It provides new experimental data on $^+$ electroproduction at high -t and compares these results with theoretical models, highlighting the limitations of GPD-based descriptions in this kinematic region.

Findings

Cross sections agree with previous JLab data.

Data align with Regge amplitude models.

Poor agreement with GPD-based models.

Abstract

Background: Measurements of exclusive meson production are a useful tool in the study of hadronic structure. In particular, one can discern the relevant degrees of freedom at different distance scales through these studies. Purpose: To study the transition between non-perturbative and perturbative Quantum Chromodyanmics as the square of four momentum transfer to the struck proton, -t, is increased. Method: Cross sections for the $^1$H(e,e'$\pi^+$)n reaction were measured over the -t range of 0.272 to 2.127 GeV$^2$ with limited azimuthal coverage at fixed beam energy of 4.709 GeV, Q$^2$ of 2.4 GeV$^2$ and W of 2.0 GeV at the Thomas Jefferson National Accelerator Facility (JLab) Hall C. Results: The -t dependence of the measured $\pi^+$ electroproduction cross section generally agrees with prior data from JLab Halls B and C. The data are consistent with a Regge amplitude based theoretical model, but show poor agreement with a Generalized Parton Distribution (GPD) based model. Conclusion: The agreement of cross sections with prior data implies small contribution from the interference terms, and the confirmation of the change in t-slopes between the low and high -t regions previously observed in photoproduction indicates the changing nature of the electroproduction reaction in our kinematic regime.