X(3872) to D bar D γ decays and the structure of X(3872)

It has been suggested that the radiative $X \to D \bar D \gamma$ decay modes are useful to shed light on the structure of the meson X(3872), since the ratio $ R={\Gamma(X \to D^+ D^- \gamma) \over \Gamma(X \to D^0 \bar D^0 \gamma)}$ is expected to be small ($R \ll 1$) if $X$ is a molecular $D^{*0} \bar D^0$ state. We compute $R$ in a $\bar c c$ $J^{PC}=1^{++}$ description of $X$ finding that it is tiny in a wide range of hadronic parameters governing the decay. A discrimination between the molecular and $\bar c c$ description can be obtained through the analysis of the photon spectrum.