Flat-top oscillons in an expanding universe

TL;DR

This paper explores flat-top oscillons in an expanding universe, providing analytic solutions, stability analysis, and their potential cosmological significance, highlighting their robustness and unique shape properties compared to traditional oscillons.

Contribution

It introduces a new class of flat-top oscillons, analyzes their stability and shape in an expanding universe, and extends understanding of their dynamics beyond small amplitude approximations.

Findings

Flat-top oscillons are more stable against collapse in 3+1 dimensions.

Their width varies non-monotonically with amplitude.

Expansion influences oscillon shape and lifetime.

Abstract

Oscillons are extremely long lived, oscillatory, spatially localized field configurations that arise from generic initial conditions in a large number of non-linear field theories. With an eye towards their cosmological implications, we investigate their properties in an expanding universe. We (1) provide an analytic solution for one dimensional oscillons (for the models under consideration) and discuss their generalization to 3 dimensions, (2) discuss their stability against long wavelength perturbations and (3) estimate the effects of expansion on their shapes and life-times. In particular, we discuss a new, extended class of oscillons with surprisingly flat tops. We show that these flat topped oscillons are more robust against collapse instabilities in (3+1) dimensions than their usual counterparts. Unlike the solutions found in the small amplitude analysis, the width of these configurations is a non-monotonic function of their amplitudes.