Extraction of bound-state parameters from dispersive sum rules |
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Authors: | W Lucha D I Melikhov and S Simula |
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Institution: | 1.Institute for High Energy Physics,Austrian Academy of Sciences,Vienna,Austria;2.Faculty of Physics,University of Vienna,Vienna,Austria;3.SINP,Moscow State University,Moscow,Russia;4.Sezione di Roma III,INFN,Roma,Italy |
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Abstract: | The procedure of extracting the ground-state parameters from vacuum-to-vacuum and vacuum-to-hadron correlators within the
method of sum rules is considered. The emphasis is laid on the crucial ingredient of this method—the effective continuum threshold.
A new algorithm to fix this quantity is proposed and tested. First, a quantum-mechanical potential model which provides the
only possibility to probe the reliability and the actual accuracy of this method is used as a study case. In this model, our
algorithm is shown to lead to a remarkable improvement of the accuracy of the extracted ground-state parameters compared to
the standard procedures adopted in the method and used in all previous applications of dispersive sum rules in QCD. As a next
step, it is demonstrated that the procedures of extracting the ground-state decay constant in the potential model and in QCD
are quantitatively very close to each other. Therefore, the application of the proposed algorithm in QCD promises a considerable
increase of the accuracy of the extracted hadron parameters. |
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