Effective continuum threshold for vacuum-to-bound-state correlators

Abstract

We formulate a new algorithm for obtaining the effective continuum threshold in vacuum-to-bound-state correlators - the basic objects for the calculation of hadron form factors in the method of light-cone sum rules in QCD. The effective continuum threshold is one of the key ingredients of the method which to a large extent determines the value of the form factor extracted from the relevant correlator. In a quantum-mechanical potential model, where the exact form factor is known, the application of our algorithm is shown to lead to a dramatic increase of the accuracy of the extracted form factor compared to the standard procedures adopted in the method of sum rules in QCD. Moreover, the application of our algorithm considerably enlarges the range of the momentum transfer where the form factor may be extracted from the correlator.