Sebastien Renaux-Petel (IAP, France)
The simplest single-field models of inflation are sufficient to explain the cosmological data. However, inflation is an ultraviolet-sensitive phenomenon, and embedding inflation into high-energy physics requires taking into account the possible effects on inflation of heavy scalar fields. Model-builders usually assume or construct potentials such that they are stabilized by a potential well. Here, we uncover a simple and universal geometrical mechanism by which these heavy fields can get destabilized. This can modify the properties or ruin otherwise successful single-field inflationary models. We illustrate this mechanism by several explicit examples.