Weak Scale in Heterotic String

Abstract

We investigate the possibility of lowering the string scale in four dimensional heterotic models possessing a non-perturbative extension of the gauge group. In particular, we consider a class of compactifications in which the perturbative gauge sector is massive, and all the gauge bosons are non-perturbative, with a coupling independent on the Planck and string scales.

Comments: Latex, 7 pages, version revised in the light of new results