Large volume susy breaking with a solution to the decompactification problem

Understand

We study heterotic ground states in which supersymmetry is broken by coupling the momentum and winding charges of two large extra dimensions to the R-charges of the supersymmetry generators.

• The large dimensions give rise to towers of heavy string thresholds that contribute to the running of the gauge couplings.
• In the general case, these contributions are proportional to the volume of the two large dimensions and invalidate the perturbative string expansion.
• The problem is evaded if the susy breaking sectors arise as a spontaneously broken phase of N=4 -> N=2 -> N=0 supersymmetry, provided that N=4 supersymmetry is restored on the boundary of the moduli space.