Unbreaking chiral symmetry

TL;DR

This paper investigates how removing low eigenmodes of the Dirac operator in QCD simulations affects chiral symmetry breaking and meson properties, showing partial symmetry restoration without losing confinement.

Contribution

It demonstrates the impact of selectively removing Dirac eigenmodes on chiral symmetry and meson mass degeneracies in a dynamical quark simulation.

Findings

Masses of $ ho$ and $a_1$ mesons become degenerate

Chiral symmetry aspects are partially restored

Confinement properties remain intact

Abstract

In Quantum Chromodynamics (QCD) the eigenmodes of the Dirac operator with small absolute eigenvalues have a close relationship to the dynamical breaking of the chiral symmetry. In a simulation with two dynamical quarks, we study the behavior of meson propagators when removing increasingly more of those modes in the valence sector, thus partially removing effects of chiral symmetry breaking. We find that some of the symmetry aspects are restored (e.g., the masses of $\rho$ and $a_1$ approach each other) while confining properties persist.