paper

Non-Gaussian tail of the curvature perturbation in stochastic ultra-slow-roll inflation: implications for primordial black hole production

arXiv:2012.06551 · doi:10.1103/PhysRevLett.127.101302

Abstract

We consider quantum diffusion in ultra-slow-roll (USR) inflation. Using the formalism, we present the first stochastic calculation of the probability distribution of the curvature perturbation during USR. We capture the non-linearity of the system, solving the coupled evolution of the coarse-grained background with random kicks from the short wavelength modes, simultaneously with the mode evolution around the stochastic background. This leads to a non-Markovian process from which we determine the highly non-Gaussian tail of . Studying the production of primordial black holes in a viable model, we find that stochastic effects during USR increase their abundance by a factor compared to the Gaussian approximation.

5+3 pages, 2 figures. v3: Corrected typos in equations

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