Quantum diffusion and large primordial perturbations from inflation

David Wands, Vincent Vennin

Research output: Chapter in Book/Report/Conference proceedingChapter (peer-reviewed)peer-review


Quantum diffusion describes the inflow of vacuum quantum fluctuations as they get amplified by gravitational instability, and stretched to large distances during inflation. In this picture, the dynamics of the universe's expansion becomes stochastic, and the statistics of the curvature perturbation is encoded in the distribution of the duration of inflation. This provides a non-perturbative framework to study cosmological fluctuations during inflation, which is well-suited to the case of primordial black holes since they originate from large fluctuations. We show that standard, perturbative expectations for the primordial black hole abundance can be significantly modified by quantum-diffusion effects, and we identify a few open challenges.
Original languageEnglish
Title of host publicationPrimordial Black Holes
EditorsChris Byrnes, Gabriele Franciolini, Tomohiro Harada, Paolo Pani, Misao Sasaki
Publication statusAccepted for publication - 6 May 2024

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