Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

F-term Axion Monodromy Inflation

Fernando Marchesano, Gary Shiu, Angel M. Uranga

TL;DR

The paper introduces F-term axion monodromy inflation as a perturbative, SUSY-friendly route to realize large-field inflation in string theory. It develops two main realizations—massive Wilson lines and closed p-form axions—where monodromy arises from fluxes or torsion and the inflaton potential originates from F-terms, with a dual 3-form structure protecting the potential from dangerous corrections. A key feature is the absence of axions in the Kähler potential, aided by a hidden gauge invariance, which alleviates the eta problem and yields well-defined endpoints for inflation. The framework yields diverse inflaton potentials, including linear, quadratic, and higher-power forms, via explicit constructions in Type II string theory with torsion or flux, and offers UV-complete templates that can accommodate observational data on primordial gravitational waves.

Abstract

The continuous shift symmetry of axions is at the heart of several realizations of inflationary models. In particular, axion monodromy inflation aims at achieving super-Planckian field ranges for the inflaton in the context of string theory. Despite the elegant underlying principle, explicit models constructed hitherto are exceedingly complicated. We propose a new and better axion monodromy inflationary scenario, where the inflaton potential arises from an F-term. We present several scenarios, where the axion arises from the Kaluza-Klein compactification of higher dimensional gauge fields (or p-form potentials) in the presence of fluxes and/or torsion homology. The monodromy corresponds to a change in the background fluxes, and its F-term nature manifests in the existence of domain walls interpolating among flux configurations. Our scenario leads to diverse inflaton potentials, including linear large field behaviour, chaotic inflation, as well as potentials with even higher powers. They provide an elegant set of constructions with properties in the ballpark of the recent BICEP2 observational data on primordial gravitational waves.

F-term Axion Monodromy Inflation

TL;DR

The paper introduces F-term axion monodromy inflation as a perturbative, SUSY-friendly route to realize large-field inflation in string theory. It develops two main realizations—massive Wilson lines and closed p-form axions—where monodromy arises from fluxes or torsion and the inflaton potential originates from F-terms, with a dual 3-form structure protecting the potential from dangerous corrections. A key feature is the absence of axions in the Kähler potential, aided by a hidden gauge invariance, which alleviates the eta problem and yields well-defined endpoints for inflation. The framework yields diverse inflaton potentials, including linear, quadratic, and higher-power forms, via explicit constructions in Type II string theory with torsion or flux, and offers UV-complete templates that can accommodate observational data on primordial gravitational waves.

Abstract

The continuous shift symmetry of axions is at the heart of several realizations of inflationary models. In particular, axion monodromy inflation aims at achieving super-Planckian field ranges for the inflaton in the context of string theory. Despite the elegant underlying principle, explicit models constructed hitherto are exceedingly complicated. We propose a new and better axion monodromy inflationary scenario, where the inflaton potential arises from an F-term. We present several scenarios, where the axion arises from the Kaluza-Klein compactification of higher dimensional gauge fields (or p-form potentials) in the presence of fluxes and/or torsion homology. The monodromy corresponds to a change in the background fluxes, and its F-term nature manifests in the existence of domain walls interpolating among flux configurations. Our scenario leads to diverse inflaton potentials, including linear large field behaviour, chaotic inflation, as well as potentials with even higher powers. They provide an elegant set of constructions with properties in the ballpark of the recent BICEP2 observational data on primordial gravitational waves.

Paper Structure

This paper contains 28 sections, 99 equations, 1 figure.

Table of Contents

  1. Introduction
  2. Axion monodromy
  3. Generalities
  4. F-term axion monodromy
  5. Massive Wilson line axion monodromy
  6. Massive Wilson lines
  7. Massive Wilson lines and torsion homology
  8. Stringy picture and D-brane T-duals
  9. A hidden gauge invariance
  10. Structure in ${\cal{N}}=1$ supersymmetry
  11. Domain wall nucleation and a maximum field range
  12. Kinetic terms and the $\eta$ problem
  13. Kinetic terms for massless Wilson lines
  14. Mixing with closed string moduli
  15. Massive Wilson lines, and a D6-brane example
  16. ...and 13 more sections

Figures (1)

  • Figure 1: a) The T-dual of a D7-brane on a Taub-NUT is a D6- and an NS5-branes at points in the T-dual circle. b) As the D6-brane crosses the NS5-brane, an stretched D4-brane is created. c) Moving to larger values of $\phi$ the D6-brane returns close to the NS5-brane. d) Creation of additional D4-branes in each crossing implies the monodromy in $\phi$. The additional brane creation in each crossing makes this construction differ from Figure 1 in am2.