Radiative decay of the X(3872) as a mixed molecule-charmonium state in effective field theory

Assuming that X(3872) is a mixture between 2P charmonium and (D) over barD* molecular states with J(PC) = 1(++), an analysis of X(3872) radiative decays into J/psi gamma and psi(2S)gamma is presented. The modification of the radiative branching ratio due to possible constructive or destructive interferences between the meson-loop and the short-distance contact term, which is modeled by a charm quark loop, is shown. The model predictions are shown to be compatible with the experimentally determined ratio of the mentioned branching fractions for a wide range of the X(3872) charmonium content. In the case of the destructive interference, a strong restriction on the charmonium admixture is found. (C) 2019 Published by Elsevier B.V.