Free Fermion Orientifolds

TL;DR

This paper explores orientifold models based on tensor products of Ising models, finding very limited three-family standard model configurations and providing a classification of resulting Hodge numbers and vacua.

Contribution

It introduces a new class of free fermion orientifold models and systematically analyzes their phenomenological and geometric properties.

Findings

No three-family models with tadpole cancellation found

Only one three-family configuration without tadpole cancellation in complex free fermions

Enumerated Hodge numbers of resulting type-IIB theories

Abstract

We investigate a class of orientifold models based on tensor products of 18 Ising models. Using the same search criteria as for the comparable case of Gepner model orientifolds we find that there are no three-family standard model configurations with tadpole cancellation. Even if we do not impose the latter requirement, we only find one such configuration in the special case of complex free fermions. In order to allow a comparison with other approaches we enumerate the Hodge numbers of the type-IIB theories we obtain. We provide indications that there are fermionic IIB vacua that are not $Z_2\times Z_2$ orbifolds.