Mutli-field open inflation and the effect of interaction on tunneling
Sugimura, Kazuyuki (YITP)

In a multi-field open inflation model, the inflaton starts slow-rolling after tunneling of another field. In previous studies, they assumed that the inflaton field does not affect the tunneling. It was not known whether multi-field instanton with gravity exists when we consider the interaction between the inflaton and the tunneling field. We find that there exists a solution for multi-field instanton. We use this solution to describe tunneling in multi-field open inflation, and solve the evolution of the universe after tunneling to make sure that slow-roll inflation lasts more than 60 e-foldings. We find a solution which realizes the multi-field open inflation scenario. We also investigate the effect of the interaction on false vacuum decay rate. Decay rate tends to increase when the effect of the interaction is taken into consideration.