Effective Continuum Thresholds for Quark-Hadron Duality in Dispersive Sum Rules

Modifying the standard approaches to nonperturbative QCD based on Borel-transformed dispersive sum rules by allowing the effective continuum thresholds required for the implementation of quark-hadron duality to depend on the Borel parameters and on any relevant momentum promises to provide higher accuracy and reliable error estimates for the extracted predictions of hadron characteristics. A careful analysis reveals that the exact effective continuum thresholds do indeed exhibit dependence on the Borel parameter (and on external momenta) and that they are not universal but vary with the correlators under consideration. The striking similarity of our hadron-parameter extraction procedures in QCD, on the one hand, and quantum-theoretical potential models, on the other hand, calls for application of the proposed techniques in QCD.