Gravitational form factors of the nucleon from the chiral effective model

TL;DR

This paper models the nucleon's gravitational form factors using a skyrmion approach within scale-invariant chiral perturbation theory, highlighting the dominant role of gluonic contributions in confining pressure and comparing results with lattice QCD.

Contribution

It introduces a novel skyrmion-based framework incorporating scalar mesons to analyze the nucleon's D-term and pressure, improving agreement with lattice QCD over traditional methods.

Findings

Gluonic contributions dominate the nucleon's confining pressure.

The model's predictions align qualitatively better with lattice QCD results.

The D-term is evaluated and compared with recent lattice and model-independent data.

Abstract

We investigate the confining pressure and associated global property, i.e, D-term, of the nucleon using the skyrmion approach formulated within scale-invariant chiral perturbation theory. In this framework, the nucleon is modeled as a skyrmion, and a scalar meson is introduced to incorporate the effects of the scale anomaly via low-energy theorems. The contributions from the current quark mass and gluonic dynamics to the scale anomaly are encoded through the pion and scalar meson masses, respectively. By decomposing the nucleon's energy-momentum tensor, we isolate the anomalous components and analyze their role in generating pressure. We find that the gluonic contribution to the scale anomaly plays a dominant role in producing confining pressure. In comparison with results from conventional chiral perturbation theory in the chiral limit, the total pressure derived from sChPT provides improved qualitative agreement with lattice QCD results. We also evaluate the D-term and compare it with recent lattice and model-independent determinations.