Symmetries of hadrons after unbreaking the chiral symmetry

TL;DR

This study investigates how hadron properties change when chiral symmetry is artificially restored in lattice QCD, revealing persistent confinement, distinct chiral multiplets, and insights into quark interactions.

Contribution

It demonstrates that confinement persists after chiral symmetry restoration and identifies higher symmetries including chiral symmetry in hadron spectra.

Findings

Most hadrons survive chiral symmetry unbreaking with improved signals.

Hadrons organize into different chiral multiplets.

Both color-magnetic and flavor-spin interactions are equally important.

Abstract

We study hadron correlators upon artificial restoration of the spontaneously broken chiral symmetry. In a dynamical lattice simulation we remove the lowest lying eigenmodes of the Dirac operator from the valence quark propagators and study evolution of the hadron masses obtained. All mesons and baryons in our study, except for a pion, survive unbreaking the chiral symmetry and their exponential decay signals become essentially better. From the analysis of the observed spectroscopic patterns we conclude that confinement still persists while the chiral symmetry is restored. All hadrons fall into different chiral multiplets. The broken U(1)_A symmetry does not get restored upon unbreaking the chiral symmetry. We also observe signals of some higher symmetry that includes chiral symmetry as a subgroup. Finally, from comparison of the \Delta - N splitting before and after unbreaking of the chiral symmetry we conclude that both the color-magnetic and the flavor-spin quark-quark interactions are of equal importance.