Possible studies on generalized parton distributions and gravitational form factors in neutrino reactions

TL;DR

This paper reviews the potential of neutrino reactions to study generalized parton distributions (GPDs) and gravitational form factors, highlighting their importance in understanding hadron structure and proposing future experimental approaches.

Contribution

It introduces the concept of using neutrino reactions for GPD measurements and discusses how this can complement existing charged-lepton experiments for hadron tomography.

Findings

Neutrino reactions can be used to probe GPDs via single-pion production.

Neutrino GPD measurements can reveal flavor dependence of GPDs.

Future neutrino experiments could enhance understanding of hadron internal structure.

Abstract

Spacelike and timelike generalized parton distributions (GPDs) have been investigated in charged-lepton scattering and electron-positron collisions via deeply virtual Compton scattering and two-photon processes, respectively. Furthermore, we expect that hadron-accelerator-facility measurements will be performed in future. The GPDs will play a crucial role in clarifying the origins of hadron spins and masses in terms of quarks and gluons. It is also possible to probe internal pressure within hadrons for understanding their stability. Gravitational form factors of hadrons used to be considered as a purely academic subject because gravitational interactions are too weak to be measured in microscopic systems. However, due to the development of hadron-tomography field, it became possible to extract the gravitational form factors from the actual GPD measurements without relying on direct gravitational interactions. Neutrino reactions can also be used for GPD studies in future, for example, by using the Long-Baseline Neutrino Facility at Fermilab. The neutrino GPD measurements are valuable especially for finding the flavor dependence of the GPDs in a complementary way to the charged-lepton experiments. We give an overview of the GPDs and discuss possible neutrino GPD measurements using the single-pion production processes $\nu + N \to \ell^- + N' + \pi$ and $\bar\nu + N \to \ell^+ + N' + \pi$.