Moduli Spaces and Target Space Duality Symmetries in $(0,2)\; Z_N$   Orbifold Theories with Continuous Wilson Lines
  We present the coset structure of the untwisted moduli space of heterotic $(0,2) \; Z_N$ orbifold compactifications with continuous Wilson lines. For the cases where the internal 6-torus $T_6$ is given by the direct sum $T_4 \oplus T_2$, we explicitly construct the K\"{a}hler potentials associated with the underlying 2-torus $T_2$. We then discuss the transformation properties of these K\"{a}hler potentials under target space modular symmetries. For the case where the $Z_N$ twist possesses eigenvalues of $-1$, we find that holomorphic terms occur in the K\"{a}hler potential describing the mixing of complex Wilson moduli. As a consequence, the associated $T$ and $U$ moduli are also shown to mix under target space modular transformations. 
G. Lopes Cardoso, D. Luest and T. Mohaupt