Local grand unification in the heterotic landscape

Abstract

We consider the possibility that the unification of the electroweak interactions and the strong force arises from string theory, at energies significantly lower than the string scale. As a tool, an effective grand unified field theory in six dimensions is derived from an anisotropic orbifold compactification of the heterotic string. It is explicitly shown that all anomalies cancel in the model, though anomalous Abelian gauge symmetries are present locally at the boundary singularities. In the supersymmetric vacuum additional interactions arise from higher-dimensional operators. We develop methods that relate the couplings of the effective theory to the location of the vacuum, and find that unbroken discrete symmetries play an important role for the phenomenology of orbifold models. An efficient algorithm for the calculation of the superpotential to arbitrary order is developed, based on symmetry arguments. We furthermore present a correspondence between bulk fields of the orbifold model in six dimensions, and the moduli fields that arise from compactifying four internal dimensions on a manifold with non-trivial gauge background.arXiv:0906.5501v2 [hep-th]

R-charge conservation and more in factorizable and non-factorizable orbifolds

“…In the presence of discrete Wilson lines, new so-called shift γ-phases appear [19,20,49]. It would be important to work out their role in the string couplings.…”

Voisin-Borcea manifolds and heterotic orbifold models

“…A standard calculation (see e.g. [32,33]) yields the massless spectrum listed in Table 3.1. The unwisted sector corresponds to k = 0, the twisted sectors are labeled by k = 1, 2, 3, 4. α, β, γ denote which fixed point locus the twisted sectors live on (see Fig.…”