Speaker: Christian Byrnes (University of Sussex)
Abstract:
It is remarkable, and disappointing, that only two parameters describing the primordial perturbations are required to explain the observed statistical properties of millions of cosmic microwave background temperature perturbations. I will give a broad overview of what this implies for the theory of inflation and how future research directions have changed following the Planck satellite results.
It remains an open question whether the primordial perturbations are due to the inflaton field, or a spectator field which did not play an active role during inflation. Despite the early universe looking very different in these two scenarios, they are still observationally degenerate today. A Bayesian model comparison between these two scenarios critically depends on the expected field value of the spectator field, and I will present recent work on calculating the expected field value of spectator fields using the stochastic formalism.