Structure of scalar mesons and the Higgs sector of strong interaction

TL;DR

This paper discusses the structure of scalar mesons and their analogy to the Higgs sector in strong interactions, proposing a unified model that explains their composition, formation, and mass predictions based on symmetry breaking.

Contribution

It introduces a comprehensive model for scalar mesons as $q^2\bar{q}^2$ states with P-wave components, aligning with experimental data and explaining their formation and mass.

Findings

Scalar mesons can be understood as $q^2\bar{q}^2$ states with P-wave components.

The P-wave component acts as a doorway state in meson formation.

Scalar meson masses are predicted through symmetry breaking mechanisms.

Abstract

The scalar mesons $\sigma(600)$, $\kappa(800)$, $f_0(980)$ and $a_0(980)$ together with the pseudo Goldstone bosons $\pi$, $K$, and $\eta$ may be considered as the Higgs sector of strong interaction. After a long time of uncertainty about the internal structure of the scalar mesons there now seems to be consistency which is in line with the major parts of experimental observations. Great progress has been made by introducing the unified model of Close and T\"ornqvist. This model states that mesons below 1 GeV may be understood as $q^2\bar{q}^2$ in S-wave with some $q\bar{q}$ in P-wave in the center, further out they rearrange as $(q\bar{q})^2$ and finally as meson-meson states. The P-wave component inherent in the structure of the neutral scalar mesons can be understood as a doorway state for the formation of the scalar meson via two-photon fusion, whereas in nucleon Compton scattering these P-wave components serve as intermediate states. The masses of the scalar mesons are predicted in terms of spontaneous and explicit symmetry breaking.