Resolving the Bethe-Salpeter kernel

TL;DR

This paper introduces a new method for constructing symmetry-consistent Bethe-Salpeter kernels that improve meson bound-state calculations by incorporating features like the dressed-quark anomalous magnetic moment.

Contribution

It presents a closed-form, symmetry-consistent Bethe-Salpeter kernel construction scheme applicable even with unknown diagrammatic content, bridging continuum and lattice approaches.

Findings

The scheme can incorporate the dressed-quark anomalous magnetic moment.

It remedies defects in common meson bound-state kernels.

Improves level ordering of pseudoscalar and vector meson excitations.

Abstract

A novel method for constructing a Bethe-Salpeter kernel for the meson bound-state problem is described. It produces a closed-form kernel that is symmetry-consistent (discrete and continuous) with the gap equation defined by any admissible gluon-quark vertex. Applicable even when the diagrammatic content of that vertex is unknown, the scheme can foster new synergies between continuum and lattice approaches to strong interactions. The framework is illustrated by demonstrating that the presence of a dressed-quark anomalous magnetic moment in the gluon-quark vertex, an emergent feature of strong interactions, can remedy many defects of widely used meson bound-state kernels, including the level ordering of pseudoscalar and vector meson radial excitations.