Bound-state properties from field-theory correlators

TL;DR

This paper explores how to accurately calculate hadron properties using QCD sum rules by analyzing systematic uncertainties and improving the method, with applications to heavy meson decay constants.

Contribution

It introduces new improvements to the QCD sum rule method for more reliable hadron parameter extraction, validated through quantum mechanics analogies and heavy meson analysis.

Findings

Controlled uncertainties in hadron parameter calculations.

Enhanced sum rule techniques for better accuracy.

Successful application to heavy meson decay constants.

Abstract

We discuss the details of calculating hadron properties from the OPE for correlators of quark currents in QCD, which constitutes the basis of the method of QCD sum rules. The main emphasis is laid on gaining control over the systematic uncertainties of the hadron parameters obtained within this method. We start with examples from quantum mechanics, where bound-state properties may be calculated independently in two ways: exactly, by solving the Schroedinger equation, and approximately, by the method of sum rules. Knowing the exact solution allows us to control each step of the sum-rule extraction procedure. On the basis of this analysis, we formulate several improvements of the method of sum rules. We then apply these modifications to the analysis of the decay constants of heavy mesons.