Symmetron Inflation

TL;DR

Symmetron Inflation proposes a natural inflationary scenario triggered by environmental density changes, utilizing a symmetron field whose potential evolves to initiate inflation without special initial conditions.

Contribution

This work introduces a novel inflation model based on symmetron fields with environment-dependent potentials, including a two-field concrete realization.

Findings

Inflation begins naturally as density drops below a critical value.

Power spectrum matches single-field slow-roll inflation.

No special initial conditions needed for inflation to start.

Abstract

We define a new inflationary scenario in which inflation starts naturally after the Big Bang when the energy density drops below some critical value. As a model, we use recently proposed symmetron field whose effective potential depends on the energy density of the environment. At high densities, right after the Big Bang, the potential for the symmetron is trivial, and the field sits in equilibrium at the bottom of the potential. When the density drops below some critical value, the potential changes its shape into a symmetry breaking potential, and the field starts rolling down. This scenario does not require any special initial conditions for inflation to start. We also construct a concrete model with two fields, i.e. with symmetron as an inflaton and an additional scalar field which describes the matter content in the early universe. For the simplest coupling, the amplitude and shape of the power spectrum are the same as in the single field slow-roll inflation.