Large Scale Structure from the Higgs fields of the Supersymmetric Standard Model

TL;DR

The paper presents a novel curvaton-like mechanism in which MSSM Higgs field isocurvature perturbations, coupled to the inflaton in a SUSY hybrid inflation model, are converted into curvature perturbations during the early reheating phase. A post-inflation generation of the μ term via a singlet vev links particle physics to cosmology, and the Higgs-driven perturbations can reproduce the observed amplitude with a spectral tilt $|n-1| \sim 0.1$, while predicting negligible non-Gaussianity and gravity-wave signals. It also allows for relic isocurvature perturbations in neutralinos and baryons, depending on the reheating details. Overall, the work connects the Higgs sector and SUSY breaking to the origin of cosmic structure, offering testable signatures in the spectral index and potential relic isocurvature modes.

Abstract

We propose an alternative implementation of the curvaton mechanism for generating the curvature perturbations which does not rely on a late decaying scalar decoupled from inflation dynamics. In our mechanism the supersymmetric Higgs scalars are coupled to the inflaton in a hybrid inflation model, and this allows the conversion of the isocurvature perturbations of the Higgs fields to the observed curvature perturbations responsible for large scale structure to take place during reheating. We discuss an explicit model which realises this mechanism in which the $μ$ term in the Higgs superpotential is generated after inflation by the vacuum expectation value of a singlet field. The main prediction of the model is that the spectral index should deviate significantly from unity, $|n-1|\sim 0.1$. We also expect relic isocurvature perturbations in neutralinos and baryons, but no significant departures from gaussianity and no observable effects of gravity waves in the CMB spectrum.

Figures (1)

• Figure 1: In the upper panel we show the evolution of the curvature ${\cal R}$ (solid line) and entropy $S_{\phi r}$ (dashed line) perturbations during reheating. Both values are normalised to the initial value of $S_{\phi r}$. We have taken $\Gamma_\phi=10^{-17} GeV^{-1}$, $V(0)^{1/4}=10^{8} \, GeV$, $\phi/h=10^{10}$ and $\eta_\phi=\eta_h$ . In the inset in the upper panel we show a blow-up of the initial region on a linear vertical scale. In the lower panel we show the evolution of the energy densities $\rho_\phi$ and $\rho_r$, normalised to their initial values.