Internal structure of the f0(980) and a0(980) mesons

Determine the internal structure of the scalar mesons f0(980) and a0(980), including whether they are two-quark states, four-quark states, meson–meson bound states, or mixtures of these configurations, through precise experimental data in the ππ and K̄K channels near 1 GeV.

Background

The paper identifies the scalar-meson sector as an important unresolved area of hadron spectroscopy. In particular, the f0(980) and its isospin-1 partner a0(980) have been assigned various possible interpretations, including two-quark configurations and K̄K bound states, but existing theoretical studies have not produced a definitive characterization.

The authors motivate precise measurements of the ππ and K̄K channels around 1 GeV, where the narrow f0(980) causes rapid amplitude variations, as a means of resolving the competing structural interpretations.

References

The internal structure of f0(980) and its partner a0(980) has been the subject of numerous theoretical studies, but none has provided a definitive characterization.

— $π$-QCD; Proposal for Experiments at the GSI Pion Beam Facility  (2609.37548 - collaboration et al., 29 Sep 2026) in Section C, subsection “Exotic mesons”