Radion stabilization in the presence of Wilson line phase
  We study the stabilization of an extra-dimensional radius in the presence of a Wilson line phase of an extra $U(1)$ gauge symmetry on a five-dimensional space-time, using the effective potential relating both the radion and the Wilson line phase at the one-loop level. We find that the radion can be stabilized by the introduction of a small number of fermions. 
Yugo Abe, Takeo Inami, Yoshiharu Kawamura, and Yoji Koyama
hep-th hep-ph