On the loop approximation in nucleon QCD sum rules

TL;DR

This paper challenges the belief that nucleon QCD sum rules with only quark loops have trivial solutions, demonstrating a nontrivial solution and discussing the impact of higher-order terms and radiative corrections.

Contribution

It introduces a nontrivial solution to nucleon QCD sum rules and analyzes the effects of higher-order terms and radiative corrections on the series convergence.

Findings

Existence of a nontrivial solution in nucleon QCD sum rules.

Higher-order terms improve series convergence.

Radiative corrections enhance the approximation.

Abstract

There was a general believe that the nucleon QCD sum rules which include only the quark loops and thus contain only the condensates of dimension d=3 and d=4 have only a trivial solution. We demonstrate that there is also a nontrivial solution. We show that it can be treated as the lowest order approximation to the solution which includes the higher terms of the Operator Product Expansion. Inclusion of the radiative corrections improves the convergence of the series.