Chern-Simons EM-flation

TL;DR

EM-flation proposes slow-roll inflation driven by a Chern-Simons coupling to antisymmetric-tensor gauge fields that acts like a magnetic field in field space, balancing the inflaton potential without requiring an ultra-flat potential. The authors develop a toy model illustrating magnetic-drift dynamics and then explore string/M-theory realizations, including D7-branes, that realize the mechanism under suitable flux and coupling hierarchies. They analyze perturbations in a D7-brane realization and show that the curvature perturbation amplitude can match observations, with a small anisotropy potentially detectable by Planck, providing a telltale signature of string theory. Overall, the work argues that EM-flation is a robust, radiatively stable inflation mechanism with broad applicability in string-inspired settings and a distinctive observational footprint.

Abstract

We propose a new, generic mechanism of inflation mediated by a balance between potential forces and a Chern-Simons interaction. Such quasi-topological interactions are ubiquitous in string theory. In the minisuperspace approximation, their effect on the dynamics can be mapped onto the problem of a charged particle in an electromagnetic field together with an external potential; slow roll arises when the motion is dominated by the analogue of `magnetic drift'. This mechanism is robust against radiative corrections. We suggest a possible experimental signature which, if observed, might be considered strong evidence for string theory.