The radiative decays $\varphi \to \gamma a_0/f_0$ in the molecular model for the scalar mesons

Abstract

We investigate the radiative decays of the $\varphi$ meson to the scalar mesons $a_0(980)$ and $f_0(980)$. We demonstrate that, contrary to earlier claims, these decays should be of the same order of magnitude for a molecular state and for a compact state and, therefore, the available experimental information is consistent with both, a molecular as well as a compact structure of the scalars. Thus, the radiative decays of the $\varphi$ meson into scalars establish a sizable $K\bar{K}$ component of the scalar mesons, but do not allow to discriminate between molecules and compact states.

Comments: 9 pages; extended discussion on finite width effects; version as published in Eur. Phys. J