The creation of radiation and the relic of inflaton potential

TL;DR

This paper proposes a new model where radiation is produced through inflaton interactions with an effective frictional force, leading to two universe expansion types and a relic inflaton potential acting as a cosmological constant.

Contribution

It introduces a novel perspective on inflaton-radiation interaction via effective friction, explaining universe expansion behaviors and the persistence of inflaton potential as a relic cosmological constant.

Findings

Type I universe reaches a uniform rolling phase with continuous particle creation.

Type II universe's inflaton becomes static, leaving a relic potential as a cosmological constant.

Inflaton potential can survive as a relic, influencing late-time cosmic acceleration.

Abstract

Recently, we have performed research on the subject of the cosmological constant problem. The scenario is based on two postulates for inflationary theory: one is that inflaton $\phi$ can interact with radiation (relativistic particles); the other is that radiation will be created continuously during and after the epoch of inflation. According to these postulates and from a "macroscopic perspective", we discover that radiation can be viewed as a product of the interaction between $\dot{\phi}$ and some "effective kinetic frictional force" that exists in inflaton dynamics. Deducing and surmising from "effective friction", we obtain conclusions of two special types of expanding universe: A Type I universe will finally enter an expanding course after a special time $t_{*}$ with uniformly rolling $\dot{\phi}(t_{*})$ due to the balance between $V^{'}(\phi(t))$, 3H(t)\dot{\phi}(t_{*}) and the "effective kinetic frictional force". In this result, the expanding course will see particles created continuously. Additionally, for a Type II universe, $\phi$ will be at rest after $t_{r}$ inside a region named the "stagnant zone" that is formed by the "maximum effective static frictional force". Consistent with this, inflaton potential will survive as a relic $V(\phi(t_{r}))$, playing the role of the effective cosmological constant $\Lambda$ .