# Supersymmetric Inflation from the Fifth Dimension

## TL;DR

This paper presents a supersymmetric bi-axion inflation model derived from extra-dimensional gauge symmetry, which naturally generates an effective super-Planckian field range and connects high-scale inflation with low-energy SUSY breaking.

## Contribution

It introduces a novel high-scale inflation model using a bi-axion structure protected by higher-dimensional gauge symmetry, compatible with low-energy supersymmetry and observable cosmological signatures.

## Key findings

- Effective super-Planckian field range from sub-Planckian dynamics
- Potential for observable non-Gaussianities in 21-cm surveys
- Periodic modulations in CMB within current measurement sensitivity

## Abstract

We develop a supersymmetric bi-axion model of high-scale inflation coupled to supergravity, in which the axionic structure originates from, and is protected by, gauge symmetry in an extra dimension. While local supersymmetry (SUSY) is necessarily Higgsed at high scales during inflation we show that it can naturally survive down to the $\sim$ TeV scale in the current era in order to resolve the electroweak hierarchy problem. We show how a suitable inflationary effective potential for the axions can be generated at tree-level by charged fields under the higher-dimensional gauge symmetry. The inflationary trajectory lies along the lightest direction in the bi-axion field space, with periodic effective potential and an effective super-Planckian field range emerging from fundamentally sub-Planckian dynamics. The heavier direction in the field space is shown to also play an important role, as the dominant source of super-Higgsing during inflation. This model presents an interesting interplay of tuning considerations relating the electroweak hierarchy, cosmological constant and inflationary superpotential, where maximal naturalness favors SUSY breaking near the electroweak scale after inflation. The scalar superpartner of the axionic inflaton, the "sinflaton", can naturally have $\sim$ Hubble mass during inflation and sufficiently strong coupling to the inflaton to mediate primordial non-Gaussianities of observable strength in future 21-cm surveys. Non-minimal charged fields under the higher-dimensional gauge symmetry can contribute to periodic modulations in the CMB, within the sensitivity of ongoing measurements.