Introduction to QCD Sum Rule Approach

TL;DR

This paper introduces the QCD sum rule approach, explaining its techniques, theoretical foundations, and applications to static and dynamic hadronic properties, including meson parameters and the pion form factor.

Contribution

It provides a comprehensive overview of the QCD sum rule method, including its extension from simple models to complex field-theoretical calculations.

Findings

Calculation of static meson parameters using sum rules

Application to the pion electromagnetic form factor

Illustration of the operator product expansion in QCD

Abstract

In these lectures, I describe the techniques used within the QCD sum rule approach. The basic concepts of the approach are introduced using a simple model of quantum-mechanical oscillator in 2+1 dimensions. Then I discuss their field-theoretical extension and the construction of the operator product expansion for current correlators in QCD. The calculation of static parameters is illustrated on the example of sum rules in the vector and axial meson channels. Finally, the QCD sum rule calculation of the pion electromagnetic form factor is presented as an example of application of the method to dynamic characteristics of the hadrons.