Wilson coefficients and four-quark condensates in QCD sum rules for medium modifications of $D$ mesons

TL;DR

This paper evaluates Wilson coefficients of four-quark condensates in QCD sum rules for D mesons, showing their limited impact on mass modifications and identifying potential order parameters for chiral symmetry breaking.

Contribution

It provides a detailed calculation of four-quark condensate contributions to QCD sum rules for D mesons, extending analysis to mass dimension six and assessing their significance.

Findings

Four-quark condensate effects are small in the Borel window.

Complete four-quark contributions help identify chiral symmetry order parameters.

Stability criteria of operator product expansions are evaluated.

Abstract

Wilson coefficients of light four-quark condensates in QCD sum rules are evaluated for pseudo-scalar $D$ mesons, thus, pushing the sum rules toward mass dimension six. Contrary to the situation for $\bar{q}q$ mesons the impact of the four-quark condensates for vacuum as well as in-medium situations is found to be rather small within the Borel window used in previous analyses. The complete four-quark condensate contributions enable to identify candidates for an order parameter of spontaneous chiral symmetry breaking/restoration as well as to evaluate stability criteria of operator product expansions.