Triality between inflation, cyclic, and phantom cosmologies

Unified phantom cosmologies

We present a general algorithm based on the concept of forminvariance which can be used for generating phantom cosmologies. It involves linear transformations between the kinetic energy and the potential of the scalar field, and transforms solutions of the EinsteinKlein-Gordon equations which preserve the weak energy condition into others which violate it, while keeping the energy density of th...

Kinetic inflation in stringy and other cosmologies.

An inflationary epoch driven by the kinetic energy density in a dynamical Planck mass is studied. In the conformally related Einstein frame it is easiest to see the demands of successful inflation cannot be satisfied by kinetic inflation alone. Viewed in the original Jordan-Brans-Dicke frame, the obstacle is manifest as a kind of graceful exit problem and/or a kind of flatness problem. These ar...

Observational constraints on phantom-like braneworld cosmologies

We investigate a simple braneworld model in which the universe contains only cold dark matter and a cosmological constant, but the effective dark energy is phantom-like because of extra-dimensional gravity effects. Modified gravity screens the cosmological constant Λ, allowing for a larger Λ. In practice, observations do not favour any significant screening. We use supernova data, the cosmic mi...

Cyclic Inflation

The Relation Between Inflation and Inflation Uncertainty In Iran