Beyond Inflation A Cyclic Universe Scenario

Universe reheating after inflation.

We study the problem of scalar particle production after inflation by an in-flaton field which is oscillating rapidly relative to the expansion of the universe. We use the framework of the chaotic inflation scenario with quartic and quadratic inflaton potentials. Particles produced are described by a quantum scalar field χ, which is coupled to the inflaton via linear and quadratic couplings. Th...

Cyclic Inflation

Generality of inflation in a planar universe.

abstract We study a generality of an inflationary scenario by integrating the Einstein equations numerically in a plane-symmetric spacetime. We consider the inhomogeneous spacetimes due to (i) localized gravitational waves with a positive cosmological constant Λ, and (ii) an inhomogeneous inflaton field Φ with a potential 1 2 m 2 Φ 2. For the case (i), we find that any initial inhomogeneities a...

An Open Universe From Inflation

We present a natural scenario for obtaining an open universe (Ω0 < 1) through inflation. In this scenario, there are two epochs of inflationary expansion—an epoch of ‘old inflation,’ during which the inflaton field is stuck in a false vacuum, followed by an epoch of ‘new inflation,’ during which the inflaton field slowly rolls toward its true minimum. During the first epoch, inflation solves th...

Designing cyclic universe models.

The phenomenological constraints on the scalar field potential in cyclic models of the Universe are presented. We show that cyclic models require a comparable degree of tuning to that needed for inflationary models. The constraints are reduced to a set of simple design rules including "fast-roll" parameters analogous to the "slow-roll" parameters in inflation.