Perturbative supersymmetry breaking in orbifolds with Wilson line backgrounds

A way to break supersymmetry in perturbative superstring theory is the string version of the Scherk-Schwarz mechanism. There, the fermions and bosons have mass splitting due to different compactification boundary conditions. We consider the implementation of this mechanism in abelian orbifold compactifications with Wilson line backgrounds. For Z(N) and Z(N) x Z(M) orbifolds, we give the possible U(1) R-symmetries which determine the mass splitting, and thus, the supersymmetry breaking at the perturbative level. The phenomenlogical viability of this mechanism implies some dimension(s) to be as large as the TeV scale. We explain how the lighter Kaluza-Klein states associated with the extra-dimension(s) have quantum numbers depending on the Wilson lines used.