Inflation with steep potentials

Abstract

The inflationary scenario remains an attractive, but by no means unique, mechanism for explaining how our observable universe evolved into its present state. The basic idea is that the energy-momentum tensor of the universe violated the strong energy condition (SEC) for a finite time interval and this caused the scale factor to accelerate with respect to cosmic time, t. Recent years have seen renewed interest in models based on a metric formulation different to that of general relativity (GR). These models modify the gravitational sectors of the theory by introducing a second scalar field which is non-minimally coupled to gravity. For example, in their ezfeuded scenario, La and Steinhardt (1989) demonstrated that the graceful exit problem of old inflation could be solved by considering a first---order phase transition within the context of the Jordan-Brans-Dicke (JBD) theory of gravitation. Unfortunately this scenario was shown to be inconsistent with time delay tests.