Brief report on `Radiative $\varphi$ decays with derivative interactions'

We study the line shapes of radiative $\varphi$-decays with a direct coupling of the $\varphi$ meson to the $f_0(980)$ and $a_0(980)$ scalar mesons. The latter couple via derivative interactions to ${\pi }_0{\pi }_0$ and ${\pi }_0\eta$, respectively. Although the kaon-loop mechanism is usually regarded as the dominant mechanism in radiative $\varphi$ decays, here we test a different possibility: we set the kaon-loop to zero and we fit the theoretical curves to the data by retaining only the direct coupling. Remarkably, satisfactory fits can be achieved, mainly due to the effects of derivative interactions of scalar with pseudoscalar mesons.