Two photon decays of scalar mesons in the quark NJL model

TL;DR

This paper calculates two-photon decay rates of scalar mesons using the quark NJL model, including meson and quark loops, and finds results consistent with experimental data.

Contribution

It introduces a detailed calculation of scalar meson decays in the NJL model, accounting for meson and quark loops at next order in 1/N_c expansion.

Findings

Meson and quark loops contribute comparably to decay amplitudes.

Kaon loops dominate in the f_0(980) to gamma gamma decay.

Results agree with recent experimental measurements.

Abstract

Two photon decays of scalar mesons f_0(980), a_0(980), \sigma(600) in the quark Nambu - Jona - Lasinio (NJL) model are calculated. The contributions of the meson loops are taken into account along with the quark loops (Hartree - Fock approximation). This corresponds to the next order of the 1/N_c expansion, where N_c=3 is the number of quark colors. It is shown that the meson and quark loops give comparable contributions to the amplitude. Moreover, in the process f_0(980)-> \gamma \gamma the kaon loop plays the dominant role. A similar situation takes place in the decay \phi -> f_0(980) \gamma \cite{physrev}. Our results are in satisfactory agreement with the recent experimental data.