  Superstring theory, models with extra dimensions and other SUSY models
generically predict that the coupling constants are in fact vacuum expectation
values of fields like the dilaton, moduli etc. Assuming some of these fields
are light during inflation, we get generation of small classical
inhomogeneities in these fields from inflation. Consequently, coupling
constants inherit small inhomogeneities at scales much larger than the causal
horizon in the early universe. After the moduli get pinned down to their
minima, the spatial variations of coupling constants in the late time universe
will be erased. However, inhomogeneities in coupling constants in the very
early universe would generate modulated large scale fluctuations in all relic
species that are produced due to interactions and freezing out. Moreover
(p)reheating of the inflaton field results in modulated curvature fluctuations.
Even if the standard inflaton fluctuations are suppressed, in this picture we
may have pure curvature cosmological fluctuations entirely generated by the
modulated spatial variations of the coupling constants during preheating.
