A systematical study of the nucleon form factors with the pion cloud effect

TL;DR

This paper investigates nucleon form factors using a covariant quark-diquark model, explicitly including pion cloud effects, and finds that pion clouds significantly influence magnetic moments and internal forces, aligning well with experimental data.

Contribution

It introduces a comprehensive covariant approach that simultaneously studies electromagnetic and gravitational form factors with explicit pion cloud effects, highlighting their importance.

Findings

Pion cloud effects are crucial for accurate magnetic moments.

Results agree with experimental and lattice data.

Pion clouds influence the sign of the D-term.

Abstract

The electromagnetic and gravitational form factors of the nucleon are studied simultaneously using a covariant quark-diquark approach, and the pion cloud effect on the form factors is explicitly discussed. In this study, the electromagnetic form factors are calculated to determine the parameters of our approach. Then, the gravitational form factors of the nucleon are evaluated with the same parameters. The electromagnetic and mechanical properties, such as charge radii, magnetic moments, and mass radii are presented. Moreover, the D-term, which is believed to be connected with the internal force inside the nucleon, is also discussed in this paper. Our results are in reasonable agreement with the experimental and lattice results, and it is suggested that the pion cloud contribution plays an indispensable role, especially for the magnetic moments and the sign of D-term.