Exceptional deconfinement in G(2)G(2) gauge theory

The Z(N)Z(N) center symmetry plays an important role in the deconfinement phase transition of SU(N)SU(N) Yang–Mills theory at finite temperature. The exceptional group G(2)G(2) is the smallest simply connected gauge group with a trivial center. Hence, there is no symmetry reason why the low- and high-temperature regimes in G(2)G(2) Yang–Mills theory should be separated by a phase transition. Still, we present numerical evidence for the presence of a first order deconfinement phase transition at finite temperature. Via the Higgs mechanism, G(2)G(2) breaks to its SU(3)SU(3) subgroup when a scalar field in the fundamental {7}{7} representation acquires a vacuum expectation value v. Varying v   we investigate how the G(2)G(2) deconfinement transition is related to the one in SU(3)SU(3) Yang–Mills theory. Interestingly, the two transitions seem to be disconnected. We also discuss a potential dynamical mechanism that may explain this behavior.