Hadronic unquenching effects in the quark propagator

TL;DR

This paper studies how the inclusion of hadronic effects, specifically the pion's back reaction, influences the quark propagator using non-perturbative continuum methods, revealing significant low-momentum modifications.

Contribution

It introduces a method to incorporate unquenching effects into the quark-gluon interaction within Schwinger-Dyson and Bethe-Salpeter frameworks, aligning with lattice results.

Findings

Significant impact on the quark mass function at low momenta

Chiral condensate shows notable changes due to unquenching

Gell-Mann-Oakes-Renner relation holds up to 400-500 MeV pion mass

Abstract

We investigate hadronic unquenching effects in light quarks and mesons. Within the non-perturbative continuum framework of Schwinger-Dyson and Bethe-Salpeter equations we quantify the strength of the back reaction of the pion onto the quark-gluon interaction. To this end we add a Yang-Mills part of the interaction such that unquenched lattice results for various current quark masses are reproduced. We find considerable effects in the quark mass function at low momenta as well as for the chiral condensate. The quark wave function is less affected. The Gell--Mann-Oakes-Renner relation is valid to good accuracy up to pion masses of 400-500 MeV. As a byproduct of our investigation we verify the Coleman theorem, that chiral symmetry cannot be broken spontaneously when QCD is reduced to 1+1 dimensions.