Formation and Decay of Oscillons in Einstein-Cartan Higgs Inflation

TL;DR

This paper reviews the formation and decay of oscillons during the preheating phase after Higgs inflation in the Einstein-Cartan framework, highlighting their transient nature and implications for early universe cosmology.

Contribution

It provides a comprehensive analysis of oscillon dynamics in Einstein-Cartan Higgs inflation, revealing their transient behavior due to self-interactions and impact on cosmic evolution.

Findings

Oscillons form after inflation due to tachyonic instabilities.

Self-interactions cause oscillons to decay, ending matter dominance.

Implications for gravitational wave production and thermal history.

Abstract

We review recent progress in the understanding of the preheating stage of Higgs inflation formulated within the Einstein-Cartan framework of gravity. This setup smoothly interpolates between the metric and Palatini formulations of the theory, leading to a distinctive phenomenology in an intermediate regime. Following the end of inflation, the Higgs field undergoes a non-trivial out-of-equilibrium evolution driven by tachyonic instabilities and nonlinear self-interactions, which fragment the inflaton condensate and give rise to well-localized oscillon configurations. While early studies suggested the formation of long-lived oscillons and the possibility of an extended matter-dominated phase, more recent analyses show that self-interactions at small field values render these objects transient, eventually triggering their decay and the onset of radiation domination. We discuss the implications of this dynamics for the thermal history of the Universe, the inflationary observables, and the generation of stochastic gravitational waves.