a_0(980) -> gamma gamma and f_0(980) -> gamma gamma: a consistent description

TL;DR

This paper uses the Linear Sigma Model to predict the two-photon decay rates of the a_0(980) and f_0(980) mesons, achieving agreement with experimental data by including a kappa meson contribution and a specific scalar mixing angle.

Contribution

It provides a consistent description of the two-photon decay rates of scalar mesons within the Linear Sigma Model, incorporating the effects of a kappa meson and scalar mixing.

Findings

Predicted decay rates match experimental data.

Inclusion of kappa meson is essential for agreement.

Scalar mixing angle is approximately -14 degrees.

Abstract

We work out the Linear Sigma Model (LSM) predictions for the 2 gamma decay rates of the a_0(980),f_0(980) mesons under the assumption that they are respectively the I=1 and I=0 members of the bar q q scalar nonet. Agreement with experimental data is achieved provided we include the contribution of a \kappa meson with mass approx. 900 MeV, and a scalar mixing angle (sigma -f_0 mixing in the {|NS>,|S>} basis) varphi_s approx. -14^\circ, as predicted by the model.