A Potential Mechanism for Inflation from Swampland Conjectures (1910.14047v5)

Abstract: Inflation is the currently accepted paradigm for the beginnings of the Universe. To explain the observed almost scale invariant spectrum of density perturbations with only a slight spectral tilt, inflation must have been "slow roll", that is with a potential with sufficiently small slope. While the origin of inflationary structure is intrinsically quantum mechanical, gravity gets treated semiclassically within inflationary models. Recent work, in terms of the so called de-Sitter swampland conjecture, has called into question whether slow roll inflation is consistent with a complete theory of quantum gravity in the presence of a positive vacuum energy density, which is a key ingredient in the inflationary paradigm. In this work, we show that, in fact, if we understand this conjecture correctly and with another swampland conjecture, the so-called distance conjecture, involved we get a potential mechanism for slow roll inflation and we argue that here fine-tuning is not a technical problem.