Electromagnetic Form Factors and Charge Radii of Pseudoscalar and Scalar Mesons: A Comprehensive Contact Interaction Analysis

TL;DR

This paper provides a comprehensive analysis of electromagnetic form factors and charge radii of various mesons using a contact interaction model that respects key QCD symmetries, enabling calculations at high virtualities.

Contribution

It introduces a simplified yet symmetry-consistent contact interaction framework for calculating meson form factors across all meson types and compares results with other methods and experiments.

Findings

Form factors computed at large photon virtualities.

Charge radii consistent with some lattice and experimental data.

Model respects Ward-Takahashi identities and confinement.

Abstract

We carry out a comprehensive survey of electromagnetic form factors of all light, heavy and heavy-light ground-state pseudoscalar and scalar mesons. Our analysis is based upon a Schwinger-Dyson equations treatment of a vector $\times$ vector contact interaction. It incorporates confinement and ensures axial vector and vector Ward-Takahashi identities are satisfied along with the corresponding corollaries such as the Goldberger-Treiman relations. The algebraic simplicity of the model allows us to compute the form factors at arbitrarily large virtualities of the probing photon momentum squared with relative ease. Wherever possible and insightful, we compare our results for the electromagnetic form factors and the charge radii with those obtained earlier through Schwinger-Dyson equations, lattice and with experimental observations available. We also comment on the scope and shortcomings of the model.