G-bounce

By D. Easson, I. Sawicki, A. Vikman. 2011

280 citations recorded by the source corpus.

We present a wide class of models which realise a bounce in a spatially flat Friedmann universe in standard General Relativity. The key ingredient of the theories we consider is a noncanonical, minimally coupled scalar field belonging to the class of theories with Kinetic Gravity Braiding / Galileon-like self-couplings. In these models, the universe smoothly evolves from contraction to expansion, suffering neither from ghosts nor gradient instabilities around the turning point. The end-point of the evolution can be a standard radiation-domination era or an inflationary phase. We formulate necessary restrictions for Lagrangians needed to obtain a healthy bounce and illustrate our results with phase portraits for simple systems including the recently proposed Galilean Genesis scenario.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/5192aa1117f4c59f10c6b10a9036043dce93b9fc

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Citations in the corpus

The Effective Field Theory of nonsingular cosmology (2016, methodology): “By adding the effective operators like R(3)δg00, (R(3))2 or ∇iR((3))∇R((3)) to the original G-bounce models [27, 47], within the framework of EFT the whole Lagrangian tends to be like the ones in eq.”
Horndeski theory and beyond: a review (2019, background): “Several examples show that instabilities may occur at the transition from the NEC-violating phase to some subsequent phase or even in a far future after the transition [100, 119, 120, 121, 122, 123, 124, 125].”
f(T) teleparallel gravity and cosmology (2015, methodology): “A nonsingular bounce solution can also be achieved by making use of matter fields with the NEC violation, such as in the quintom bounce [392–394], the Lee-Wick bounce [395, 396], the ghost condensate bounce [397–399], the braneworld bounce [400–402], the Galileon bounce [403, 404], and the bounce mo”
Exploring bouncing cosmologies with cosmological surveys (2014, background): “The Galileon model might realize a nonsingular bounce as well, but was found to suffer from a severe graceful-exit problem from the bouncing phase to the phase of regular thermal expansion [107, 108].”
Generalized Galileons: instabilities of bouncing and Genesis cosmologies and modified Genesis (2016, background): “Likewise, bouncing Universe models with generalized Galileons can be arranged in such a way that no ghost or gradient instabilities occur at and near the bounce [20–23].”
The Matter Bounce Alternative to Inflationary Cosmology (2012, unknown): “An improved way of obtaining a non-singular bouncing cosmology using modified matter is by using a ghost condensate field [67] (see also [68] for related work).”
Generic instabilities of nonsingular cosmologies in Horndeski theory: A no-go theorem (2016, background): “In some cases the universe can experience a healthy bounce, but then the solution has some kind of singularity in the past or future [19].”
hi_class: Horndeski in the Cosmic Linear Anisotropy Solving System (2016, unknown): “[69] for example phase-space trajectories in cosmology).”
Maximal freedom at minimum cost: linear large-scale structure in general modifications of gravity (2014, background): “When αB 6= 0, the region of phase space where D = 0 represents a pressure singularity [47] and no trajectory ever evolves across it [80].”
Towards a nonsingular bouncing cosmology (2012, background): “In this section, we present a nonsingular bouncing solution in terms of a single field having the desirable features of both the ghost condensate and Galileon-inspired models.”