Evaluation of the Nucleon Helicity Flip Form Factor using One and Two Virtual Photons

TL;DR

This paper investigates the nucleon helicity flip form factor at high momentum transfer by analyzing one- and two-photon exchange processes, combining QCD perturbation theory with nucleon distribution amplitudes, revealing divergent results and their structure.

Contribution

It introduces a method combining QCD perturbation theory with nucleon distribution amplitudes to evaluate the form factor, including analysis of divergences and their implications.

Findings

Divergent results for the form factor are obtained.

The structure of divergences can be extracted from the calculations.

Behavior of the form factor in unpolarized and polarized cross sections is discussed.

Abstract

In this work, we will evaluate the nucleon helicity flip form factor at the limit of large momentum transfer. Hereby, we will study the exchange of one and two virtual photons separately. For the calculation of the scattering amplitudes and nucleon transition probability matrix elements, we combine QCD perturbation theory with an expansion in nucleon distribution amplitudes. Using the combination of leading and sub-leading twist nucleon distribution amplitudes, one obtains the desired form factor. Using this technique, we will obtain a divergent result for the form factor. Nevertheless, the structure of the divergency can be extracted. Finally, we will comment the obtained expressions and discuss the behavior in unpolarized and polarized cross sections.