Bouncing Galileon Cosmologies
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In this article, nonsingular, homogeneous and isotropic bouncing solutions of the conformal Galileon model were presented, and it was shown that such solutions necessarily begin with a radiation-dominated contracting phase.Abstract:
We present nonsingular, homogeneous and isotropic bouncing solutions of the conformal Galileon model. We show that such solutions necessarily begin with a radiation-dominated contracting phase. This is followed by a quintom scenario in which the background equation of state crosses the cosmological constant boundary allowing for a nonsingular bounce which in turn is followed by Galilean Genesis. We analyze the spectrum of cosmological perturbations in this background. Our results show that the fluctuations evolve smoothly and without any pathology, but the adiabatic modes form a blue tilted spectrum. In order to achieve a scale-invariant primordial power spectrum as required by current observations, we introduce a light scalar field coupling to the Galileon kinetically. We find two couplings which yield a scale-invariant spectrum, one of which requires a fine tuning of the initial conditions. This model also predicts a blue tilted spectrum of gravitational waves stemming from quantum vacuum fluctuations in the contracting phase.read more
Citations
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Non-singular bounce scenarios in loop quantum cosmology and the effective field description
Yi-Fu Cai,Edward Wilson-Ewing +1 more
TL;DR: In this article, the authors compare the dynamics in loop quantum cosmology and in a non-singular bouncing effective field model with a nonstandard kinetic term at both the background and perturbative levels.
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An extended matter bounce scenario: current status and challenges
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TL;DR: In this article, an extended model of the matter bounce cosmology is proposed, in which the universe has experienced a quasi-matter contracting phase with a variable background equation of state parameter.
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Hidden Negative Energies in Strongly Accelerated Universes
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TL;DR: In this paper, it was shown that theories of cosmological acceleration which have equation of state, w, such that 1+w is small but positive may still secretly violate the null energy condition.
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Dynamical analysis of generalized Galileon cosmology
Genly Leon,Emmanuel N. Saridakis +1 more
TL;DR: In this paper, a detailed dynamical analysis of generalized Galileon cosmology, incorporating also the requirements of ghost and instabilities absence, was performed, and it was shown that there are not any new stable late-time solutions apart from those of standard quintessence.
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The Effective Field Theory of nonsingular cosmology: II
TL;DR: Based on the Effective Field Theory (EFT) of cosmological perturbations, the authors explicitly clarified the pathology in nonsingular cubic Galileon models and showed how to cure it in EFT with new insights into this issue.
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4D Gravity on a Brane in 5D Minkowski Space
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TL;DR: In this paper, the authors present in a manifestly gauge-invariant form the theory of classical linear gravitational perturbations in part I, and a quantum theory of cosmological perturbation in part II.