RadiativeX0Decays in BrokenSU(3)

The radiative decays of the $X^0$ meson are analyzed in the framework of an effective Lagrangian with vector-meson dominance, using vector gauge fields with current mixing and assuming $X^0$ to be a unitary singlet. The underlying $\mathrm{VVP}$ strong interaction obeys octet-broken $\mathrm{SU}\left(3\right)\mathrm{}$ symmetry. The model is shown to predict branching ratios different from those obtained in the $\eta -X^0$ mixing model. An analysis of the experimental situation is presented, and the relevance of the $X^0\to 2\gamma$, $X^0\to \omega \gamma$ partial decay modes for distinguishing between different theoretical models is pointed out.