Signatures of Supersymmetry from the Early Universe
Daniel Baumann, Daniel Green
TL;DR
The paper addresses how SUSY can protect scalar fields during inflation and leaves Hubble-scale isocurvatons that leave imprints in the squeezed limit of the primordial bispectrum.It develops a supersymmetric effective theory of inflation (SUSY EFT) to classify inflaton interactions with additional fields and to evaluate naturalness.It applies the framework to both supersymmetric small-sound-speed (P(X)) theories and to supersymmetric quasi-single-field inflation (QSFI), showing that SUSY can render otherwise tuning-sensitive scenarios natural and yield distinctive squeezed-limit signatures.The results highlight observational prospects for using cosmology to probe SUSY and present concrete SUSY QSFI realizations with testable predictions for CMB and large-scale structure.
Abstract
Supersymmetry plays a fundamental role in the radiative stability of many inflationary models. Spontaneous breaking of the symmetry inevitably leads to fields with masses of order the Hubble scale during inflation. When these fields couple to the inflaton they produce a unique signature in the squeezed limit of the three-point function of primordial curvature perturbations. In this paper, we make this connection between naturalness, supersymmetry, Hubble-mass degrees of freedom and the squeezed limit precise. To study the physics in a model-insensitive way, we develop a supersymmetric effective theory of inflation. We use the effective theory to classify all possible interactions between the inflaton and the additional fields, and determine which ones naturally allow large non-Gaussianities when protected by supersymmetry. Finally, we discuss the tantalizing prospect of using cosmological observations as a probe of supersymmetry.