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University of Cambridge > Talks.cam > Cosmology Lunch > Stochastic effective theory for scalar fields in de Sitter space
Stochastic effective theory for scalar fields in de Sitter spaceAdd to your list(s) Download to your calendar using vCal
If you have a question about this talk, please contact Francesco. Zoom link: https://zoom.us/j/96497850096. The stochastic Starobinsky-Yokoyama approach is a powerful non-perturbative effective description of long-wavelength dynamics of a scalar field in de Sitter spacetime. It is based on the observation that on superhorizon distances the field behaves classically, with a noise term produced by subhorizon quantum modes. The approach has been mostly used to calculate the one-point probability distribution of the field, but its real power lies in describing the asymptotic long-distance behaviour of correlation functions through a spectral expansion. I demonstrate this by calculating isocurvature constraints for scalar dark matter models and decay rates of metastable vacua. I also show how to extend the stochastic theory beyond the overdamped approximation used by Starobinsky and Yokoyama. The parameters of this effective theory are determined at one-loop order in perturbation theory, and do not suffer from the same infrared problems as a direct perturbative computation of observables. Therefore the stochastic theory provides a powerful and accurate way of computing cosmological observables. This talk is part of the Cosmology Lunch series. This talk is included in these lists:
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