Hybridgen: A Model for the Study of QCD Hybrid States
  We study the mixing of excited states of a Hydrogen atom in a cavity with de-excited states plus a confined photon as a model for the coupling of quark-antiquark and quark-antiquark-gluon hybrid states in QCD. For an interesting range of parameters, the results are analytic. We find a case for which wavefunctions (and hence decay patterns) may be at odds with mass with respect to identification of a state as hybrid or not. 
M.M. Brisudova (Nuclear Theory Center, Indiana U) and T. Goldman   (Theoretical Division, Los Alamos National Laboratory)