Transition to order after hilltop inflation

Abstract

We investigate the rich nonlinear dynamics during the end of hilltop inflation by numerically solving the coupled Klein-Gordon-Friedmann equations in a expanding universe. In particular, we search for coherent, nonperturbative configurations that may emerge due to the combination of nontrivial couplings between the fields and resonant effects from the cosmological expansion. We couple a massless field to the inflaton to investigate its effect on the existence and stability of coherent configurations and the effective equation of state at reheating. For parameters consistent with data from the Planck and WMAP satellites, and for a wide range of couplings between the inflaton and the massless field, we identify a transition from disorder to order characterized by emergent oscillonlike configurations. We verify that these configurations can contribute a maximum of roughly 30% of the energy density in the universe. At late times their contribution to the energy density drops to about 3%, but they remain long-lived on cosmological time-scales, being stable throughout our simulations. Cosmological oscillon emergence is described using a new measure of order in field theory known as relative configurational entropy.

Gravitational Waves from Oscillons after Inflation

“…For example, φ can be identified with an order parameter of a second order phase transition, where some symmetry gets spontaneously broken. The universe inflates while φ rolls away from the maximum at φ = 0 and inflation ends when the curvature of the potential becomes too large and the inflaton accelerates toward v. Around the minimum at φ = v, the potential is highly asymmetric, with an inflection point toward the plateau for φ < v and steeper than quadratic for φ > v. Thus, such potentials support oscillons only on one side, φ < v. As mentioned above, oscillons in this type of potential form after inflation [10,11], when the inflaton accelerates toward the minimum and undergoes a series of tachyonic oscillations, periodically crossing the inflection point at φ < v. These oscillons are then separated by a characteristic distance related to the frequency of the tachyonic oscillations, which is proportional to the mass of the inflaton around the minimum m φ ∝ √ V 0 /v. The above scenario is very minimal, and ties V 0 to the amplitude of the curvature perturbation A s once v is fixed.…”

“…Oscillons can be produced during preheating after different models of inflation [7][8][9][10][11], as well as in various types of field theories [12][13][14][15][16][17][18][19]. In [20], it has been shown that they form when a scalar field oscillates in a potential that opens up away from the minimum, i.e.…”

End of inflation, oscillons, and matter-antimatter asymmetry

“…The connection between Q-balls and baryogensis has been discussed extensively in the literature [40]. Oscillons have been found in a number of reheating studies as well (for example [5,37,42,43]). In this paper, our focus has been inflaton fragmentation, soliton formation and asymmetry generation within the context of the scenario in [16]: inflationary asymmetry generation due to a small breaking of global U (1) symmetry.…”

Information content inF(R)brane models with nonconstant curvature

“…The approach presented in [22] has been used to study the non-equilibrium dynamics of spontaneous symmetry breaking [23], to obtain the stability bound for compact objects [24], to investigate the emergence of localized objects during inflationary preheating [25], and moreover, to distinguish configurations with energy-degenerate spatial profiles [26]. Furthermore, in a recent work [27], solitons, Lorentz symmetry breaking, supersymmetry, and entropy, were employed using the CE concept.…”