Non-gaussianities for primordial black hole formation

We analyze primordial non-gaussianities in presence of an ultra-slow phase during the inflationary dynamics, focusing on scenarios relevant for the production of primordial black holes. We compute the three-point correlation function of comoving curvature perturbations finding that non-gaussianities are sizable, and predominantly local. In the context of threshold statistics, we analyze their impact for the abundance of primordial black holes, and their interplay with the non-gaussianities arising from the non-linear relation between density and curvature perturbations. We find that non-gaussianities significantly modify the estimate of the primordial black holes abundance obtained with the gaussian approximation. However, we show that this effect can be compensated by a small change, of a factor 2o3 at most, of the amplitude of the primordial power spectrum of curvature perturbations. This is obtained with a small tuning of the parameters of the inflationary model.

Automated summary

The study analyzes the impact of primordial non-gaussianities in the presence of an ultra-slow phase during inflationary dynamics, focusing on scenarios relevant for the production of primordial black holes. By computing the three-point correlation function of comoving curvature perturbations, it is found that non-gaussianities are significant and mainly local, affecting the estimated abundance of primordial black holes obtained with the Gaussian approximation. However, it is shown that this effect can be compensated by slightly adjusting the amplitude of the primordial power spectrum of curvature perturbations through a small tuning of the parameters of the inflationary model.