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arXiv · 2210.05201

Primordial non-Guassianity in inflation with gravitationally enhanced friction

Li-Yang Chen·Hongwei Yu·Puxun Wu
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Abstract

The gravitationally enhanced friction can reduce the speed of the inflaton to realize an ultra-slow-roll inflation, which will amplify the curvature perturbations. The amplified perturbations can generate a sizable amount of primordial black holes (PBHs) and induce simultaneously a significant background gravitational waves (SIGWs). In this paper, we investigate the primordial non-Gaussianity of the curvature perturbations in the inflation with gravitationally enhanced friction. We find that when the gravitationally enhanced friction plays a role in the inflationary dynamics, the non-Gaussianity is noticeably larger than that from the standard slow-roll inflation. During the regime in which the power spectrum of the curvature perturbations is around its peak, the non-Gaussianity parameter changes from negative to positive. When the power spectrum is at its maximum, the non-Gaussianity parameter is near zero ($\sim \mathcal{O}(0.01)$). Furthermore, the primordial non-Gaussianity promotes the formation of PBHs, while its effect on SIGWs is negligible.

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Li-Yang Chen, Hongwei Yu, Puxun Wu. 2022-10-11. Primordial non-Guassianity in inflation with gravitationally enhanced friction. https://doi.org/10.1103/physrevd.106.063537

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