Three-Generation Super No-Scale Models in Heterotic Superstrings

Abstract

We derive the conditions for the one-loop contribution to the cosmological constant to be exponentially suppressed in a class of heterotic string compactifications with three generations of chiral matter, where supersymmetry is spontaneously broken à la Scherk-Schwarz. Using techniques of partial unfolding based on the Hecke congruence subgroup Γ 0 (2) of the modular group to extract the leading asymptotics, we show that the super no-scale condition n B = n F between the degeneracies of massless bosons n B and fermions n F in the full string spectrum is necessary but not sufficient, and needs to be supplemented by additional conditions which we identify. We use these results to construct three-generation Pati-Salam models with interesting phenomenological characteristics.