Multifield Dynamics of Higgs Inflation

TL;DR

This paper investigates the multifield dynamics of Higgs inflation with nonminimal coupling, showing that multifield effects diminish rapidly, leading to predictions consistent with single-field models and recent observations.

Contribution

It provides a detailed analysis of multifield effects in Higgs inflation, demonstrating their rapid damping and confirming the robustness of single-field predictions.

Findings

Multifield effects damp out quickly after inflation begins.

Predictions align with single-field models and recent measurements.

The methods apply to any multifield model with nonminimal couplings and SO(N) symmetry.

Abstract

Higgs inflation is a simple and elegant model in which early-universe inflation is driven by the Higgs sector of the Standard Model. The Higgs sector can support early-universe inflation if it has a large nonminimal coupling to the Ricci spacetime curvature scalar. At energies relevant to such an inflationary epoch, the Goldstone modes of the Higgs sector remain in the spectrum in renormalizable gauges, and hence their effects should be included in the model's dynamics. We analyze the multifield dynamics of Higgs inflation and find that the multifield effects damp out rapidly after the onset of inflation, because of the gauge symmetry among the scalar fields in this model. Predictions from Higgs inflation for observable quantities, such as the spectral index of the power spectrum of primordial perturbations, therefore revert to their familiar single-field form, in excellent agreement with recent measurements. The methods we develop here may be applied to any multifield model with nonminimal couplings in which the ${\cal N}$ fields obey an $SO ({\cal N})$ symmetry in field space.