Moduli fields , a natural prediction of any supergravity and superstring-inspired supersymmetry theory , may lead to a prolonged period of matter domination in the early Universe .
This can be observationally viable provided the moduli decay early enough to avoid harming nucleosynthesis .
If primordial black holes form , they would be expected to do so before or during this matter dominated era .
We examine the extent to which the standard primordial black hole constraints are weakened in such a cosmology .
Permitted mass fractions of black holes at formation are of order 10 ^ { -8 } , rather than the usual 10 ^ { -20 } or so .
If the black holes form from density perturbations with a power-law spectrum , its spectral index is limited to n \lesssim 1.3 , rather than the n \lesssim 1.25 obtained in the standard cosmology .