Nucleon Gravitational Form Factors

TL;DR

This paper uses symmetry-preserving quantum field analysis to unify the understanding of pion, kaon, and nucleon form factors, revealing insights into pressure distributions, parton separations, and proton radii.

Contribution

It provides a unified, symmetry-preserving analysis of strong interaction form factors, offering new predictions on pressure, parton ratios, and proton radii.

Findings

Pion near-core pressure is about twice that of the proton.

Glue-to-quark ratio in nucleon gravitational form factors is constant across momentum transfer.

Proton mechanical radius is smaller than its charge radius.

Abstract

A symmetry-preserving analysis of strong interaction quantum field equations is used to complete a unified treatment of pion, kaon, nucleon electromagnetic and gravitational form factors. Findings include a demonstration that the pion near-core pressure is roughly twice that in the proton, so both are significantly greater than that of a neutron star; parton species separations of the nucleon's three gravitational form factors, in which, inter alia, the glue-to-quark ratio for each form factor is seen to take the same constant value, independent of momentum transfer; and a determination of proton radii orderings, with the mechanical (normal force) radius being less than the mass-energy radius, which is less than the proton charge radius. This body of predictions should prove useful in an era of anticipated experiments that will enable them to be tested.