Generalized string functions of N = 1 space-time supersymmetric string vacua

Abstract

We present a dual formulation of the construction of N = 2 nonlinear σ-model type conformal field theories with c = 9 which are mainly used as internal sectors of Calabi-Yau heterotic string compactifications. The supercurrents G ±( z) and the higher components of the spectral flow superfields X ±( z) + θ ± Y ±( z) turn out in each case to be tensor products of two simple currents of a c = 1 and a non-supersymmetric parafermionic c = 8 CFT. The characters of the latter model can be regarded as string functions of the coset σ U(1) . In particular, for the (1) 9 Gepner model we discuss these string functions in detail, realizing this model contains a broken E 8 gauge symmetry of which only the abelian subalgebra remains a symmetry of the spectrum. As an example, we construct a simple model leading to a string theory with a massless spectrum of 36 E 6 generations and an extended gauge symmetry E 6 × SU(3) 4.