Studying pion effects in the quark propagator

TL;DR

This study uses Schwinger-Dyson and Bethe-Salpeter equations to analyze how pions influence the quark propagator, revealing significant effects on the quark mass function and chiral condensate.

Contribution

It introduces a pion-inclusive truncation of the quark-gluon vertex that aligns with lattice results and respects chiral symmetry constraints.

Findings

Pion back reaction significantly impacts the quark mass function.

The chiral condensate is notably affected by pion effects.

The quark wave function remains relatively unchanged.

Abstract

Within the framework of Schwinger-Dyson and Bethe-Salpeter equations we investigate the importance of pions for the quark-gluon interaction. To this end we choose a truncation for the quark-gluon vertex that includes intermediate pion degrees of freedom and adjust the interaction such that unquenched lattice results for various current quark masses are reproduced. The corresponding Bethe-Salpeter kernel is constructed from constraints by chiral symmetry. After extrapolation to the physical point we find a considerable contribution of the pion back reaction to the quark mass function as well as to the chiral condensate. The quark wave function is less affected.