Universality of multi-field alpha attractors [1711.09478 [hep-th]]
by
Yvette Welling
→
Europe/Berlin
Description
The Planck data reveal that the inflationary perturbations are Gaussian, adiabatic and almost scale-invariant to a high level of accuracy. A possible explanation for this observed simplicity is that inflation is driven by a single scalar field with small self-interactions. However, UV embeddings of inflation typically contain multiple scalar fields besides the inflaton, with non-standard kinetic terms.
Therefore, it is important to understand which building blocks of multi-field models of inflation are successful in the light of the observational data. In this discussion we focus on the role of the hyperbolic field space, a geometry which arises naturally in string compactifications. In particular, we consider a two-field generalization of the so-called alpha attractors. The key property of the single field alpha attractors is that their predictions are insensitive to considerable deformations of the potential, due to the stretching induced by the hyperbolic geometry. In the paper we show that the universality extends to the two-field scenario as well. This result lends support to the idea that not all moduli fields have to be stabilised necessarily in order to have a successful model of inflation.