Non-compact symmetries and scalar masses in superstring-inspired models

We show that one-loop corrections in the presence of broken supersymmetry do not generate gauge non singlet scalar masses in no-scale supergravity models that possess a partial invariance under a non-compact Heisenberg group of global transformations. This invariance is a remnant of an invariance of ten-dimensional supergravity that survives in some compactification schemes. We discuss the conditions under which compactification of a ten-dimensional superstring theory yields a Heisenberg symmetry