Non-Gaussian signatures of multi-field inflation from string theory
Final Report Abstract
The standard model of physical cosmology relies on a very early phase of accelerated expansion called inflation which can successfully explain the observed isotropy of our universe on large scales as well as the statstical distribution of temperature anisotropies in the cosmic microwave background radiation (CMBR) and of the large-scale structure of galaxies. In its simplest form, it can be described in terms of a single scalar field, the inflaton. On the other hand, introducing several inflaton fields (“multi-field inflation”) is both theoretically plausible and phenomenologically interesting. The goal of this project was an investigation of the theoretical and phenomenological consequences of multi-field inflation. In short, significant progress was made on the former and relatively little on the latter. Beginning with the latter, the primary observational consequence of multi-field inflation is the production of non-Gaussian signatures in the CMBR which were strongly constrained by the Planck satellite mission approximately one year into the project. For personal reasons, the original goal of modelling the CMBR bi-spectrum with modal methods was not reached by us. One publication was published on the topic of non-Gaussianities. It predicts oscillatory signals in the CMBR power and bi-spectrum in a class of two-field inflation models that generically appears in the so-called open inflation scenario. On the theoretical side, the project concentrated on multi-field inflation with random potentials and their modelling by Dyson Brownian motion potentials. In collaboration with D. Battefeld and local bachelor and master students we worked on different consequences of random potential theory in multi-field inflation and published seven refereed articles.
