Modular Symmetries of Threshold Corrections for Abelian Orbifolds with   Discrete Wilson Lines
  The modular symmetries of string loop threshold corrections for gauge coupling constants are studied in the presence of discrete Wilson lines for all examples of abelian orbifolds, where the point group is realised by the action of Coxeter elements or generalised Coxeter elements on the root lattices of the Lie groups. 
A.Love, S.Todd