Two or Four: A Hint from Scalar Mesons in Radiative phi Decays ?

TL;DR

This paper analyzes radiative decays involving light scalar mesons using the vector meson dominance model, highlighting difficulties in distinguishing quark configurations and discussing the fit of experimental data with different interaction models.

Contribution

It provides a recent analysis of scalar meson radiative decays, comparing quark models and examining the effects of different interactions and loops on experimental data.

Findings

Derivative-type $f_0 Kar{K}$ interaction fits data below 950 MeV

Poor fit around 980 MeV without $K$ loop effects

Discrepancies around $a_0(980)$ can be mitigated by $K$ loop contributions

Abstract

In this write-up, we summarize our recent analysis of radiative decays involving light scalar mesons. Our analysis using the vector meson dominance model at tree level indicates that it may be difficult to distinguish $qq\bar{q}\bar{q}$ picture and $q\bar{q}$ picture for the light scalar nonet. Our result on the process of $\phi \to \pi^0 \eta \gamma$ shows that the derivative-type $f_0 K\bar{K}$ interaction reproduces experimental data below 950 GeV well, but gives a poor fit above 950 GeV, i.e., in the energy region around the mass of $a_0(980)$, but that the discrepancy can be compensated by the effect of the $K$ loop.