Who: Ricardo Ferreira (CP3-Origins)
When: Wednesday, October 21, 2015
In this thesis I address the role of gauge fields in the early universe. I focus on their inflationary dynamics and in which way they can lead to observational signatures today, either by generating strong magnetic fields, observable tensor modes or significant non-Gaussianities.
The observation of strong magnetic fields on the largest scales of our observable universe may require a non-trivial inflationary mechanism to generate them. I investigate generalizations of some benchmarks ideas and study whether they ameliorate the standard problems of inflationary magnetogenesis. I verify that some scenarios greatly improve, compared to previous studies, the maximal magnetic field generated compatible with observations.
Furthermore, I also look for observational signatures of an axial coupling between pseudo-scalar fields and gauge fields. In particular, I show that the production of non-Gaussianity strongly constraints previous ideas on generating large tensor modes through this coupling. From this analysis I derive universal constraints on the decay rate of axions during inflation, which represents an interesting constraint on more fundamental theories.