Decay of light scalar mesons into vector-photon and into pseudoscalar mesons

TL;DR

This paper analyzes the decay processes of light scalar mesons into vector-photon and pseudoscalar mesons, comparing tetraquark and quarkonium models, and discusses implications for their internal structure.

Contribution

It provides a comparative analysis of decay mechanisms in tetraquark and quarkonium models, favoring the tetraquark assignment based on decay patterns and theoretical considerations.

Findings

Tetraquark assignment better explains $S o PP$ decays.

Experimental results can distinguish between quark-loop and kaon-loop contributions.

Tetraquark model is favored over molecular interpretations for $a_{0}(980)$ and $f_{0}(980)$.

Abstract

The decays of a light scalar meson into a vector meson and a photon ($S\to V\gamma)$ are evaluated in the tetraquark and quarkonium assignments of the scalar states. A link with the radiative decays $\phi\to S\gamma$ is established: experimental results for $S\to V\gamma$ will allow to understand if the direct, quark-loop contribution to $\phi\to S\gamma$ or the kaon-loop contribution is dominant. Also strong decays $S\to PP$ -where $P$ denotes a pseudoscalar meson- are investigated: the tetraquark assignment works better than the quarkonium one. It is then also discussed why the tetraquark assignment is favoured with respect to a loosely bound kaonic molecular interpretation of $a_{0}(980)$ and $f_{0}(980)$ mesons.