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Stochastic inflationary dynamics beyond slow-roll and consequences for primordial black hole formation

2020; Institute of Physics; Volume: 2020; Issue: 08 Linguagem: Inglês

10.1088/1475-7516/2020/08/043

1475-7516

Guillermo Ballesteros, Julián Rey, Marco Taoso, Alfredo Urbano,

Galaxies: Formation, Evolution, Phenomena

We consider the impact of quantum diffusion on inflationary dynamics during an ultra-slow-roll phase, which can be of particular significance for the formation of primordial black holes. We show, by means of a fully analytical approach, that the power spectrum of comoving curvature perturbations computed in stochastic inflation matches precisely, at the linear level, the result obtained by solving the Mukhanov-Sasaki equation, even in the presence of an ultra-slow-roll phase. We confirm this result numerically in a model in which the inflaton has a polynomial potential and is coupled quadratically to the Ricci scalar. En route, we assess the role that quantum noise plays in the presence of an ultra-slow-roll phase, and clarify the issue of the quantum-to-classical transition in this scenario.