$SU(2N_F)$ symmetry of confinement in QCD and its observation at high temperature

TL;DR

This paper discusses the observation of new SU(2N_F) and SU(2)_{CS} symmetries in QCD related to confinement, their emergence at high temperature, and their implications for the nature of quark interactions in the deconfined phase.

Contribution

It provides lattice evidence for the emergence of larger symmetries in QCD upon truncation of near-zero modes and at high temperature, revealing the dominance of chromo-electric interactions.

Findings

Emergence of SU(2N_F) and SU(2)_{CS} symmetries in lattice QCD

Chromo-magnetic effects are confined to near-zero modes

High-temperature phase involves quarks bound by chromo-electric fields

Abstract

In this talk we first overview lattice results that have led to the observation of new SU(2)_{CS} and SU(2N_F) symmetries upon artificial truncation of the near-zero modes of the Dirac operator at zero temperature and at high temperature without any truncation. These symmetries are larger than the chiral symmetry of the QCD Lagrangian and contain chiral symmetries SU(N_F)_L \times SU(N_F)_R and U(1)_A as subgroups. In addition to the standard chiral transformations the SU(2)_{CS} and SU(2N_F) transformations mix the right- and left-handed components of the quark fields. It is a symmetry of the confining chromo-electric interaction while the chromo-magnetic interaction manifestly breaks it. Emergence of these symmetries upon truncation of the near-zero modes of the Dirac operator at T=0 means that all effects of the chromo-magnetic interaction are located exclusively in the near-zero modes, while confining chromo-electric interaction is distributed among all modes. Appearance of these symmetries at high T, where the temperature suppresses the near-zero modes, has radical implications because these symmetries are incompatible with the asymptotically free deconfined quarks at increasing temperature. The elementary objects in the high-temperature phase of QCD should be quarks bound by the pure chromo-electric field that is not accompanied by the chromo-magnetic effects.