Covariant fermionic and heterotic strings from the bosonic string

Abstract

We discuss the embedding of the covariantly formulated superstring and heterotic string theories into the 26-dimensional bosonic string. The construction is based on equalities among bosonic and fermionic one-loop partition functions and, in particular, shows how the one-loop partition function of the superconformal ghost system can be obtained from the compactified bosonic string. It provides a natural expression for the covariant fermion vertex operator in the context of the bosonic string. We also discuss the necessary truncations which are needed to obtain the covariant heterotic string by compactification of the bosonic string on self-dual lattices.