Radiative decays with light scalar mesons and singlet-octet mixing in ChPT

TL;DR

This paper investigates radiative decays involving light scalar mesons using ChPT at one-loop level, aiming to clarify their flavor structure and predict decay widths relevant for ongoing experiments.

Contribution

It provides a unified ChPT-based analysis of scalar meson decays, determines the mixing angle consistent with experiments, and predicts unmeasured decay widths and relations between decay processes.

Findings

Determined the scalar meson mixing angle consistent with experimental data.

Predicted decay widths for f0(980)/a0(980) to gamma rho and omega.

Derived model-independent relations between decay widths.

Abstract

We study different types of radiative decays involving f0(980) and a0(980) mesons within a unified ChPT-based approach at one-loop level. Light scalar resonances which are seen in pi pi, pi eta, K K-bar channels of phi(1020) radiative decays and in J/psi decays are responsible for key questions of low-energy dynamics in the strong interaction sector, and decays phi(1020) -> gamma a0(980), phi(1020) -> gamma f0(980), a0(980) -> gamma gamma, f0(980) -> gamma gamma are of interest for current experimental programs in Juelich, Frascati and Novosibirsk. From theoretical point of view it is important to verify whether light scalar mesons are members of some flavor octet or nonet. We find a value of mixing angle dictated by consistency with experiment and coupling structures of ChPT Lagrangian. Decay widths f0(980)/a0(980) -> gamma rho(770)/omega(782), which are not studied experimentally yet, are predicted. We also obtain several relations between widths, which hold independently of coupling constants and represent a fingerprint of the model.