Non-critical heterotic superstrings in various dimensions

We construct heterotic string theories on spacetimes of the form Rd-1,1 x N = 2 linear dilation, where d = 6,4,2,0. There are two lines of supersymmetric theories descending from the two supersymmetric ten-dimensional heterotic theories. These have gauge groups which are lower rank subgroups of E8 x E8 and SO(32). On turning on a (2, 2) deformation which makes the two dimensional part a smooth SL2 (R)/U(1) supercoset, the gauge groups get broken further. In the deformed theories, there are non-trivial moduli which are charged under the surviving gauge group in the case of d = 6. We construct the marginal operators on the worldsheet corresponding to these moduli. (author)