  We consider black hole formation due to the gravitational collapse produced
by large density fluctuations during an epoch of reheating with a stiff
equation of state and calculate the induced gravitational wave spectrum. By
considering the existing bounds on the total energy density of gravitational
waves today, we find constraints on the parameter space of this scenario. We
also calculate the lepton asymmetry generated by metric perturbations via the
chiral gravitational anomaly present in the Standard Model and find that, once
the electroweak sphaleron processes have taken place, the large spectrum of
scalar perturbations responsible for black hole formation induces a peak in the
baryon asymmetry fluctuations on small scales.
