Ground-state spectrum of light-quark mesons

Abstract

A confining, Goldstone theorem preserving, separable ansatz for the ladder kernel of the two-body Bethe-Salpeter equation is constructed from phenomenologically efficacious $u$, $d$, and $s$ dressed-quark propagators. The simplicity of the approach is its merit. It provides a good description of the ground-state flavor-octet pseudoscalar, vector, and axial-vector meson spectrum facilitates an exploration of the relative importance of various components of the two-body Bethe-Salpeter amplitudes, showing that subleading Dirac components are quantitatively important in the flavor-octet pseudoscalar meson channels, and allows a scrutiny of the domain of applicability of ladder truncation studies. A color-antitriplet diquark spectrum is obtained. The shortcomings of separable Ans\"atze and the ladder kernel are highlighted.