Coupling constants of $D^*D_sK$ and $D_s^*DK$ processes
  We calculate the coupling constants of $D^*D_sK$ and $D_s^*DK$ vertices using the QCD sum rules technique. We compare results obtained in the limit of SU(4) symmetry and found that the symmetry is broken on the order of 40%. 
M.E. Bracco, A. Lozea, A. Cerqueira Jr., M. Chiapparini and M. Nielsen