A Unitarity-Conserving Higgs Inflation Model

TL;DR

This paper introduces a new Higgs inflation model that preserves unitarity at high energies by adding derivative interactions, predicting a spectral index of 0.974, and discusses the importance of supersymmetry or a singlet scalar for quantum stability.

Contribution

A novel unitarity-conserving Higgs inflation model with derivative interactions, differing in spectral index prediction and addressing high-energy unitarity issues.

Findings

Model maintains unitarity at inflation energies.

Predicts spectral index n=0.974.

Highlights need for supersymmetry or singlet scalars for quantum corrections.

Abstract

Scalar field models of inflation based on a large nonminimal coupling to gravity xi, in particular, Higgs inflation, may violate unitarity at an energy scale ~ M_p / xi << M_p. In this case the model is incomplete at energy scales relevant to inflation. Here we propose a new unitarity-conserving model of Higgs inflation. The completion of the theory is achieved via additional interactions which are proportional to products of the derivatives of the Higgs doublet. The resulting model differs from the original version of Higgs inflation in its prediction for the spectral index, with a classical value n = 0.974. In the case of a nonsupersymmetric model, quantum corrections are likely to strongly modify the tree-level potential, suggesting that supersymmetry or a gauge singlet scalar inflaton is necessary for a completely successful model.