  Even with recent progress, it is still very much an open question to
understand how all compactification moduli are stabilized, since there are
several mechanisms. For example, it is possible to generate a scalar potential
either classically or through nonperturbative effects, such as gaugino
condensation. Such a potential can stabilize certain of the moduli fields, for
example the dilaton. On the other hand, a background of thermal matter with
moduli-dependent masses can also stabilize certain of the moduli, e.g., the
radion. It is important to understand whether these two distinct mechanisms are
compatible with each other, that is, that there are no interference terms that
could spoil the moduli stabilization. In this paper, we study heterotic string
theory on an N=1 orbifold near an enhanced symmetry point. We then consider
both a nonperturbatively generated potential and a gas of strings with
moduli-dependent masses to stabilize the dilaton and radial modulus,
respectively. We conclude that, given certain approximations, these two moduli
stabilization mechanisms are compatible.
