N=2 -> 0 super no-scale models and moduli quantum stability

Understand

We consider a class of heterotic N=2 -> 0 super no-scale Z_2-orbifold models.

• An appropriate stringy Scherk-Schwarz supersymmetry breaking induces tree level masses to all massless bosons of the twisted hypermultiplets and therefore stabilizes all twisted moduli.
• At high supersymmetry breaking scale, the tachyons that occur in the N=4 -> 0 parent theories are projected out, and no Hagedorn-like instability takes place in the N=2 -> 0 models (for small enough marginal deformations).
• At low supersymmetry breaking scale, the stability of the untwisted moduli is studied at the quantum level by taking into account both untwisted and twisted contributions to the 1-loop effective potential.