The role of pions as virtual constituents of light bound states

TL;DR

This paper investigates how pions influence the structure and spectrum of light mesons and tetraquarks using a functional QCD approach, revealing significant pion cloud effects and predicting an all-charm tetraquark around 5.5 GeV.

Contribution

It extends Dyson-Schwinger and Bethe-Salpeter equation methods to include pion cloud effects and explores tetraquark states, including an all-charm tetraquark prediction.

Findings

Pion cloud effects significantly impact light meson properties.

Identification of an all-charm tetraquark around 5.5 GeV.

Enhanced understanding of light hadron spectra in a functional QCD framework.

Abstract

We summarize recent results for the spectrum and properties of light pseudoscalar and scalar hadrons in a functional approach to QCD using Dyson-Schwinger and Bethe-Salpeter equations. We focus in particular on the role of pions as virtual constituents in light mesons ('pion cloud effects') as well as their role as constituents of tetraquark bound states. An extension of our framework into the charm quark sector reveals an all-charm tetraquark in the mass region around 5.5 GeV.