Reconclining phi radiative decays with other data for a0(980), fo(980), pi-pi -> KK and pi-pi -> eta-eta

TL;DR

This paper analyzes phi radiative decays using the KK loop model, compares parameters of a0(980) and fo(980) with experimental data, and discusses interference effects and additional scalar contributions in meson decay processes.

Contribution

It provides a detailed comparison of phi decay data with scalar meson parameters, highlighting the need for interference effects and additional scalar states like sigma and fo(1370).

Findings

Eta-pi mass spectrum matches well with model predictions.

Discrepancy in phi -> gamma pi0 pi0 normalization suggests interference effects.

Evidence for sigma and fo(1370) contributions in pi-pi scattering data.

Abstract

Data for phi -> gamma (eta-pizero) are analysed using the KK loop model and compared with parameters of a0(980) derived from Crystal Barrel data. The eta-pi mass spectrum agrees closely and the absolute normalisation lies just within errors. However, BES parameters for fo(980) predict a normalisation for phi -> gamma (pizero-pizero) at least a factor 2 lower than is observed. This discrepancy may be eliminated by including constructive interference between fo(980) and sigma. The magnitude required for sigma -> KK is consistent with data on pi-pi -> KK. A dispersion relation analysis by Buttiker, Descotes-Genon and Moussallam of pi-pi -> KK leads to a similar conclusion. Data on pi-pi -> eta-eta also require decays of sigma to eta-eta. Four sets of pi-pi -> KK data all require a small but definite fo(1370) signal.