Seminar S. Hardeman

S. Hardeman
Supergravity consequences for inflationary cosmology

The inflationary paradigm is very successful in explaining at the same time the large scale homogeneity and isotropy of the universe as well as the small scale perturbations that are observed by the cosmic microwave background experiments COBE and WMAP. The measurements of WMAP are still well explained by the simplest single-field model. With the upcoming observations of even more precise measurements by the Planck satellite we might hope to constrain the parameter space enough to exclude large classes of models, and thus provide us with a unique probe of the physics during inflation. As inflation is expected to have happened at very high energies of order 10^{14} GeV, it is natural to search for an embedding in UV-complete models like string theory. At these energies, most UV-complete models are well described by an effective supergravity theory. That begs the question which restrictions supergravity puts on inflationary models. In this talk I will discuss several issues supergravity has, such as the presence of gravitationally coupled (heavy) hidden sectors that might destabilise the vacuum, generating a new finetuning problem or causing backreactions on the light inflaton. I will argue that single field inflation is unnatural from a supergravity perspective, and that by studying the CMB we might learn valuable lessons about supergravity.

Thursday, October 28, 2010 - 12:30 - 13:30