Charmed Pseudoscalar and Vector Mesons: a Comprehensive QCD Sum-Rule   View of Their Decay Constants
  In spite of undeniable similarities of the applied techniques, somewhat different challenges are encountered when extracting, from QCD sum rules derived from two-point correlators of appropriate interpolating heavy-light quark currents, the decay constants of charmed mesons of pseudoscalar nature, on the one hand, or of vector nature, on the other hand. This observation justifies a rather careful reassessment of the corresponding results. 
Wolfgang Lucha, Dmitri Melikhov, Silvano Simula
hep-ph