Bethe–Salpeter equations: mesons beyond the rainbow-ladder truncation

Abstract

We investigate masses of light mesons from a coupled system of Dyson–Schwinger (DSE) and Bethe–Salpeter equations (BSE), taking into account dominant non-Abelian, sub-leading Abelian, and dominant pion cloud contributions to the dressed quark-gluon vertex. The axial-vector Ward–Takahashi identity preserving Bethe–Salpeter kernel is constructed and the spectrum of light mesons calculated. Our model goes significantly beyond the rainbow-ladder. We find that sub-leading Abelian corrections are further dynamically suppressed, and that our results supersede early qualitative predictions from simple truncation schemes.