Preheating in Einstein-Cartan Higgs Inflation: Oscillon formation

TL;DR

This paper uses lattice simulations to study preheating in Einstein-Cartan Higgs Inflation, revealing oscillon formation that affects early universe evolution and generates gravitational waves beyond current detection capabilities.

Contribution

It demonstrates for the first time the formation of oscillons during preheating in Einstein-Cartan Higgs Inflation using 3+1D lattice simulations, highlighting their impact on cosmology.

Findings

Oscillons constitute up to 70% of energy density.

Prolonged matter domination due to oscillon formation.

Gravitational wave signals are generated but beyond current detection range.

Abstract

We make use of classical lattice simulations in 3 + 1 dimensions to study the preheating stage of Higgs Inflation in Einstein-Cartan gravity. Focusing for concreteness on a simplified scenario involving the seminal Nieh-Yan term, we demonstrate the formation of dense and spatially localized oscillon configurations constituting up to 70% of the total energy density. The emergence of these meta-stable objects may lead to a prolonged period of matter domination, effectively modifying the post-inflationary history of the Universe as compared to the metric and Palatini counterparts. Notably, the creation of oscillons comes together with a significant gravitational wave signal, whose typical frequency lies, however, beyond the range accessible by existing and planned gravitational wave experiments. The impact of the Standard Model gauge bosons and fermions and the potential extension of our results to more general Einstein-Cartan settings is also discussed.