Classification of the [formula omitted] type II orbifolds and their type II asymmetric duals

Abstract

Using free world-sheet fermions, we construct and classify all the N = 2, Z 2 × Z 2 four-dimensional orbifolds of the type IIA/B strings for which the orbifold projections act symmetrically on the left- and right-movers. We study the deformations of these models out of the fermionic point, deriving the partition functions at a generic point in the moduli of the internal tours T 6 = T 2 × T 2 × T 2. We investigate some of their perturbative and non-perturbative dualities and construct new dual pairs of type IIA/type II asymmetric orbifolds, which are related non-perturbatively and allow us to gain insight into some of the non-perturbative properties of the type IIA/B strings in four dimensions. In particular, we consider some of the (non)-perturbative gravitational corrections.