Theory Group Seminar, 07 February 2017

Dr. Jason Pollack, Caltech

How Decoherence Affects the Probability of Slow-Roll Eternal Inflation

abstract

Slow-roll inflation can become eternal if the quantum variance of the inflaton field around its slowly rolling classical trajectory is converted into a distribution of classical spacetimes inflating at different rates, and if the variance is large enough compared to the rate of classical rolling that the probability of an increased rate of expansion is sufficiently high. Both of these criteria depend sensitively on whether and how perturbation modes of the inflaton interact and decohere. Decoherence is inevitable as a result of gravitationally-sourced interactions whose strength are proportional to the slow-roll parameters. However, the weakness of these interactions means that decoherence is typically delayed until several Hubble times after modes pass the Hubble scale. I show how to modify the standard picture of eternal inflation to reflect this delayed decoherence.