Theory Seminar

De Sitter Vacua and Inflation in no-scale String Models

by Christian Gross (Universitaet Dortmund)



I will talk about the question of how de Sitter vacua and slow-roll inflation may be realized in string-motivated models. More specifically, I consider 4d N=1 supergravity theories with Kähler potentials which are `no-scale' at leading order. Such theories frequently arise in the moduli sector of string compactifications. I start by discussing a condition on the Kähler potential and on the direction of supersymmetry breaking in field space, which has to be met in order for the scalar potential to admit a local minimum, respectively a trajectory which is sufficiently flat for inflation. While this condition turns out to be rather restrictive for no-scale Kähler potentials, it can nevertheless be satisfied for certain no-scale models with more than one modulus. I will present explicit two-moduli models, with superpotentials which could arise from flux backgrounds and non-perturbative effects, which have a viable vacuum without employing subleading corrections or an uplifting sector.