Constraints in the context of induced-gravity inflation

Abstract

Constraints on the required flatness of the scalar potential $V\left(\phi \right)$ for a cousin model to extended inflation are studied. It is shown that, unlike earlier results, induced-gravity inflation can lead to successful inflation with a very simple Lagrangian and $\lambda \sim {10}^6$, rather than ${10}^{-15\mathrm{}}$ as previously reported. A second order phase transition further enables this model to escape the "big bubble" problem of extended inflation, while retaining the latter's motivations based on the low-energy effective Lagrangians of supergravity, superstring, and Kaluza-Klein theories.