Higgs-Palatini Inflation and Unitarity

Abstract

In the Higgs inflation scenario the Higgs field is strongly coupled to the Ricci scalar in order to drive primordial inflation. However, in its original form in pure metric formulation of gravity, the ultraviolet (UV) cutoff of the Higgs interactions and the Hubble rate are of the same magnitude, and this makes the whole inflationary evolution dependent of the unknown UV completion of the Higgs sector. This problem, the unitarity violation, plagues the Higgs inflation scenario. In this letter we show that, in the Palatini formulation of gravitation, Higgs inflation does not suffer from unitarity violation since the UV cutoff lies parametrically much higher than the Hubble rate so that unknown UV physics does not disrupt the inflationary dynamics. Higgs-Palatini inflation, as we call it, is, therefore, UV-safe, minimal and endowed with predictive power.

14 pages, discussion enhanced, references added, accepted by PLB

References in corpus (9)

• The Standard Model Higgs boson as the inflaton
• Power-counting and the Validity of the Classical Approximation During Inflation
• Inflation with Non-Minimal Coupling: Metric vs. Palatini Formulations
• Unitarizing Higgs Inflation
• Unifying Einstein and Palatini gravities
• Palatini versus metric formulation in higher curvature gravity
• Remarks on Higgs Inflation
• First-order Formalism and Odd-derivative Actions
• Indistinguishable Macroscopic Behaviour of Palatini Gravities and General Relativity