Coupled-channel analysis of the X(3872)

Abstract

The X(3872) is studied as an axial-vector charmonium state in the multichannel framework of the Resonance-Spectrum-Expansion quark-meson model, previously applied to a variety of other puzzling mesonic resonances. Included are the open-charm pseudoscalar-vector and vector-vector channels, the most important of which is the S-wave $\bar{D}^{*0}D^{0}$ + $D^{*0}\bar{D}^{0}$ channel, which practically coincides with the X(3872) structure. The two free parameters of the model are tuned so as to roughly reproduce the $\chi_{c1}(3511)$ mass as well as the enhancement just above the $\bar{D}^{*0}D^{0}$ / $D^{*0}\bar{D}^{0}$ threshold. The present model is able to describe the shape of the latter data quite well. However, as no dynamical resonance pole is found, the X(3872) and X(3940) cannot be reproduced simultaneously, at this stage. A possible further improvement is discussed.