Vacuum structure of an eight-dimensional $SU(3)$ gauge theory on a magnetized torus

TL;DR

This paper studies the vacuum structure of an eight-dimensional $SU(3)$ gauge theory compactified on a magnetized torus, analyzing how matter fields and Wilson line phases influence the low-energy spectrum and stability.

Contribution

It introduces matter fields into the model and demonstrates how Wilson line phases can stabilize the vacuum by removing tachyonic states, supported by one-loop effective potential calculations.

Findings

Wilson line phases affect the mass spectrum of low-energy modes.

Matter fields enable the existence of stable vacuum configurations.

Potentially tachyonic states can be eliminated with appropriate Wilson line phases.

Abstract

We analyze the vacuum structure of an eight-dimensional non-abelian gauge theory with a compactified four-dimensional torus as the extra dimensions. As a non-trivial background configuration of the gauge field of an $SU(n)$ gauge group, we suppose a magnetic flux in two extra dimensions, and continuous Wilson line phases are also involved. We introduce matter fields and calculate the mass spectrum of low-energy modes appearing in a four-dimensional effective theory in an $SU(3)$ model as an explicit example. As expected, potentially tachyonic states in four-dimensional modes appear from extra-dimensional gauge fields that couple to the flux background since the gauge group is simply connected. The Wilson line phases give a non-vanishing contribution to their masses, and we have a low-energy mass spectrum without tachyonic states, given that these phases take an appropriate value. To verify the validity of the values of the Wilson line phases, we examine the one-loop effective potential for these phases and explicitly show the contribution from each type of field present in our model. It is clarified that, although there seems to be no local minimum in the potential for the Wilson line phases in the pure Yang-Mills case, by including matter fields, we could find a vacuum configuration where tachyonic states disappear.