On Hybrid Monodromy Inflation (Hic Sunt Dracones)

TL;DR

This paper analyzes two-field hybrid inflation models, focusing on a Stewart prototype, examining their compatibility with current CMB data, stability under quantum corrections, and proposing mechanisms involving axions and strong dynamics for natural inflation.

Contribution

It investigates the stability of hybrid inflation models to quantum corrections and proposes a mechanism using axions and strong dynamics to support natural hybrid inflation.

Findings

Current CMB data constrains the model parameters.

Quantum corrections require additional stabilization mechanisms.

Axion and strong dynamics can naturally support hybrid inflation.

Abstract

We revisit two-field hybrid inflation as an effective field theory for low-scale inflation with sub-Planckian scalar field ranges. We focus on a prototype model by Stewart because it allows for a red spectral tilt, which still fits the current data. We describe the constraints on this model imposed by current CMB measurements. We then explore the stability of this model to quantum corrections. We find that for relevant, marginal, and at least a finite set of irrelevant operators, some additional mechanism is required to render the model stable to corrections from both quantum field theory and quantum gravity. We outline a possible mechanism by realizing the scalars as compact axions dual to massive $4$-form field strengths, and outline how natural hybrid inflation may be supported by strong dynamics in the dual theory.