Flat-top oscillons in an expanding universe

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.Comment: v2-matches version published in Phys. Rev D. Updated references and minor modification to section 4.

Transition to order after hilltop inflation

“…[11,23,24,[28][29][30][31][32]) indicate that the emergence of ordered structures is a very general feature of preheating for potentials that support them. Their presence delays thermodynamic equipartition since they "lock" long wavelength modes for a long time.…”

“…[24]. The potential role of oscillons in cosmology has been investigated in 1d simulations [25][26][27][28], while 3d simulations have been carried out for a single real field in a double-well potential [29], for hybrid inflation [30], and for φ 6 potentials [31], where the emergence of flat-top oscillons [28] was reported. Formation of oscillons after inflation for realistic inflationary potentials was investigated in [32], which prompted one of the questions we address here: whether couplings to other fields destabilize oscillons over time scales shorter than those associated with quantum mechanical decays [33].…”

Gravitational waves from Affleck-Dine condensate fragmentation

“…The "open-up" condition for Q-balls to form is very similar to that of oscillons [44]. Oscillons [45] are also localized, spherically symmetric, time dependent field configurations, and can be produced from fragmentation of an inflaton condensate in preheating [46].…”

End of inflation, oscillons, and matter-antimatter asymmetry

“…We find that the oscillons are ∼ 10m late in phase with a frequency m. The detailed profiles of oscillons and their lifetimes [22,[50][51][52], interactions [53,54], their size distribution [42,55] etc. will be studied elsewhere.…”

“…We will show that when nonlinearities in the potential are present, the asymmetry can be qualitatively and quantitatively different from the homogeneous scenario. Moreover, the fragmentation leads to copious formation of pseudo-solitonic configurations (oscillons [19][20][21][22][23]) after inflation which lock up most of the energy density as well as the asymmetry. Some of these oscillons have an inflaton excess, others have an anti-inflaton excess.…”