Exceptional Confinement in G(2) Gauge Theory

TL;DR

This paper explores the unique confinement properties of G(2) gauge theories, highlighting their similarities and differences with QCD, including screening effects, phase structure, and lattice simulation results.

Contribution

It provides a comprehensive analysis of G(2) gauge theories, including their confinement mechanisms, symmetry breaking, and lattice calculations, extending understanding beyond traditional QCD.

Findings

G(2) gauge theories confine without a center symmetry.

String breaking occurs due to screening by gluons.

Lattice calculations reveal key features of G(2) confinement.

Abstract

We study theories with the exceptional gauge group G(2). The 14 adjoint "gluons" of a G(2) gauge theory transform as {3}, {3bar} and {8} under the subgroup SU(3), and hence have the color quantum numbers of ordinary quarks, anti-quarks and gluons in QCD. Since G(2) has a trivial center, a "quark" in the {7} representation of G(2) can be screened by "gluons". As a result, in G(2) Yang-Mills theory the string between a pair of static "quarks" can break. In G(2) QCD there is a hybrid consisting of one "quark" and three "gluons". In supersymmetric G(2) Yang-Mills theory with a {14} Majorana "gluino" the chiral symmetry is Z(4)_\chi. Chiral symmetry breaking gives rise to distinct confined phases separated by confined-confined domain walls. A scalar Higgs field in the {7} representation breaks G(2) to SU(3) and allows us to interpolate between theories with exceptional and ordinary confinement. We also present strong coupling lattice calculations that reveal basic features of G(2) confinement. Just as in QCD, where dynamical quarks break the Z(3) symmetry explicitly, G(2) gauge theories confine even without a center. However, there is not necessarily a deconfinement phase transition at finite temperature.