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

Abstract

It has been suggested that the radiative $X \to D \bar D γ$ decay modes are useful to shed light on the structure of the meson X(3872), since the ratio $ R={Γ(X \to D^+ D^- γ) \over Γ(X \to D^0 \bar D^0 γ)}$ 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.