A double-running inflaton mass for a flat potential and an assisted hilltop inflation

TL;DR

This paper introduces a novel assisted hilltop inflation model where a renormalization group running involving an assisting field flattens the inflaton potential, addressing initial condition and flatness issues in small-field inflation.

Contribution

It proposes a new inflation scenario with a double-running inflaton mass, utilizing an assisting field to naturally set initial conditions and flatten the potential.

Findings

Inflaton potential can be flattened by the vacuum expectation value of an assisting field.

The scenario naturally resolves initial condition and flatness problems.

The model is applicable to small-field slow-roll inflation.

Abstract

We propose a scenario to flatten inflaton potential for a small-field slow-roll inflation from the origin. In the scenario, inflaton mass-square gets through a renormalization group running which depends on not only inflaton field but also an assisting field. Thanks to the assisting field participating in the running, initial condition for a slow-roll inflation can be set naturally, and inflaton potential can be flattened by the vacuum expectation value of the field. Applying this idea, we propose a scenario of inflation, dubbed here as \textit{assisted hilltop inflation}, which is free from the initial condition and the flatness problems of inflation.