Classifications of the free fermionic heterotic string vacua

Abstract

The existence of discrete properties is shown in the landscape of the Free-Fermionic Heterotic-String vacua. These were discovered via the classification of the SO(10) GUT gauge group and its subgroups, such as, the Pati-Salam, the Flipped SU(5) and the SU(4)×SU(2)×U(1) models. The classification is carried out by fixing a set of basis vectors and then varying the GGSO projection coefficients entering the one-loop partition function. The analysis of the models is facilitated by deriving algebraic expressions for the GGSO projections to enable a computerised analysis of the entire String spectrum and the scanning of large spaces of vacua. The analysis reveals an abundance of 3 generation models with exophobic String vacua. This is observed with the SO(10) and the Pati-Salam models. Contrary to this, the Flipped SU(5) models contained no exophobic vacua with an odd number of generations. Moreover, it is also observed that the SU(4)×SU(2)×U(1) models are substantially more constrained and that no generations exist. The analysis of the SU(3)×U(1)×SU(2)×U(1) and the SU(3)×U(1)×SU(2)×SU(2) models are being examined, which is work in progress, that are expected to generate further interesting phenomenology