ON QUARK-HADRON DUALITY IN THE HEAVY-QUARK SECTOR

I discuss possible failures of local quark-hadron duality in the syste m of heavy-light quark mesons. As an example, I consider a correlator of two currents comprising heavy quark operators, and I compare the OP E expression with the result obtained by a complete insertion of hadro nic states. After a smearing procedure, OPE and hadronic spectral func tions agree with each other. However, the local behaviour of the two f unctions is different, and the difference manifests itself in a term w hich is absent in the OPE.