Iason Baldes (ENS Paris)

Cosmological relics in the presence of small scale curvature perturbations

Inflation, reheating, or other very early universe physics, may have resulted in enhanced power in small scale curvature perturbations. These will be searched for by future CMB experiments looking for spectral distortions and by gravitational wave observatories. This motivates further study of particle physics scenarios, beyond primordial black hole production, in the presence of such perturbations. I will discuss recent work in this direction in the well-known scenarios of the freeze-out of dark matter, and the heavy states of leptogenesis models, from such a radiation bath. We show oscillatory perturbations do not result in large primary effects regarding the relic density. Nevertheless, this illuminates known but under-explored research directions, e.g. the possibility of follow-on effects such as entropy production via diffusion damping of the perturbations playing a leading role in setting the dark matter relic density.