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arXiv · 1807.09057

Failure of the stochastic approach to inflation beyond slow-roll

Diego Cruces·Cristiano Germani·Tomislav Prokopec
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Abstract

After giving a pedagogical review we clarify that the stochastic approach to inflation is generically reliable only at zeroth order in the (geometrical) slow-roll parameter $\epsilon_1$ if and only if $\epsilon_2^2\ll 6/\epsilon_1$, with the notable exception of slow-roll. This is due to the failure of the stochastic $\Delta N$ formalism in its standard formulation. However, by keeping the formalism in its regime of validity, we showed that, in ultra-slow-roll, the stochastic approach to inflation reproduces the power spectrum calculated from the linear theory approach.

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Diego Cruces, Cristiano Germani, Tomislav Prokopec. 2018-07-24. Failure of the stochastic approach to inflation beyond slow-roll. https://doi.org/10.1088/1475-7516%2F2019%2F03%2F048

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