Canonical description of cosmological backreaction

Bojowald, Martin; Ding, Ding

doi:10.1088/1475-7516/2021/03/083

Cited by 24 publications

(27 citation statements)

References 45 publications

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“…whose components are given as the solutions to Equation (36). For convenience, we introduce the new variables c(φ) := ( ã1 ã2 ã3 )…”

Section: Field Equation On the Dressed Anisotropic Backgroundmentioning

confidence: 99%

“…Notice that in simplifying equations above, we have used the relations between components according to Equation (36).…”

Section: Field Equation On the Dressed Anisotropic Backgroundmentioning

confidence: 99%

“…where ξ is a parameter that distinguishes the anisotropic solutions from the isotropic one and depends on the conditions imposed on the additional unknown variables ãi 's and ki 's of the system in Equation (36). The case ξ 2 = 1 associates with the isotropic solution, whereas the case ξ = 1 denotes the anisotropic solutions (cf.…”

Section: Field Equation On the Dressed Anisotropic Backgroundmentioning

confidence: 99%

“…On such backgrounds, the standard approach for studying the infinite number of field modes fails, and an alternative procedure should be employed (e.g., see [35]). For other approaches in canonical quantum gravity, where the quantum theory of cosmological perturbations and their backreactions are implemented, see, e.g., [36][37][38][39][40][41][42].…”

Section: Gravitational Particle Productionmentioning

confidence: 99%

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Cosmological Particle Production in Quantum Gravity

Tavakoli

2021

Universe

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Quantum theory of a test field on a quantum cosmological spacetime may be viewed as a theory of the test field on an emergent classical background. In such a case, the resulting dressed metric for the field propagation is a function of the quantum fluctuations of the original geometry. When the backreaction is negligible, massive modes can experience an anisotropic Bianchi type I background. The field modes propagating on such a quantum-gravity-induced spacetime can then unveil interesting phenomenological consequences of the super-Planckian scales, such as gravitational particle production. The aim of this paper is to address the issue of gravitational particle production associated with the massive modes in such an anisotropic dressed spacetime. By imposing a suitable adiabatic condition on the vacuum state and computing the energy density of the created particles, the significance of the particle production on the dynamics of the universe in Planck era is discussed.

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“…whose components are given as the solutions to Equation (36). For convenience, we introduce the new variables c(φ) := ( ã1 ã2 ã3 )…”

Section: Field Equation On the Dressed Anisotropic Backgroundmentioning

confidence: 99%

“…Notice that in simplifying equations above, we have used the relations between components according to Equation (36).…”

Section: Field Equation On the Dressed Anisotropic Backgroundmentioning

confidence: 99%

Section: Field Equation On the Dressed Anisotropic Backgroundmentioning

confidence: 99%

Section: Gravitational Particle Productionmentioning

confidence: 99%

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Cosmological Particle Production in Quantum Gravity

Tavakoli

2021

Universe

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“…For such a purpose, we will perform a decomposition of the wavefunction into its infinite set of moments following the framework first presented in [28]. This formalism is very useful to understand the dynamics of peaked semiclassical states and it has already been applied to the analysis of a variety of cosmological models; see, e.g., [29]- [38].…”

Section: Introductionmentioning

confidence: 99%

Quantum Kasner transition in a locally rotationally symmetric Bianchi II universe

Alonso-Serrano,

Brizuela,

Uria

2021

Preprint

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The Belinski-Khalatnikov-Lifshitz (BKL) conjecture predicts a chaotic alternation of Kasner epochs in the evolution of generic classical spacetimes towards a spacelike singularity. As a first step towards understanding the full quantum BKL scenario, we analyze a vacuum Bianchi II model with local rotational symmetry, which presents just one Kasner transition. During the Kasner epochs, the quantum state is coherent and it is thus characterized by constant values of the different quantum fluctuations, correlations and higher-order moments. By computing the constants of motion of the system we provide, for any peaked semiclassical state, the explicit analytical transition rules that relate the parametrization of the asymptotic coherent state before and after the transition. In particular, we obtain the modification of the transition rules for the classical variables due to quantum back-reaction effects. This analysis is performed by considering a high-order truncation in moments (the full computations are performed up to fifth-order, which corresponds to neglecting terms of an order 3 ), providing a solid estimate about the quantum modifications to the classical model. Finally, in order to understand the dynamics of the state during the transition, we perform some numerical simulations for an initial Gaussian state, that show that the initial and final equilibrium values of the quantum variables are connected by strong and rapid oscillations.

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Kink-antikink scattering in a quantum vacuum

Mukhopadhyay

Sfakianakis

Vachaspati

et al. 2022

J. High Energ. Phys.

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We study kink-antikink scattering in the sine-Gordon model in the presence of interactions with an additional scalar field, ψ, that is in its quantum vacuum. In contrast to the classical scattering, now there is quantum radiation of ψ quanta and the kink-antikink may form bound states that resemble breathers of the sine-Gordon model. We quantify the rate of radiation and map the parameters for which bound states are formed. Even these bound states radiate and decay, and eventually there is a transition into long-lived oscillons.

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Canonical description of cosmological backreaction

Cited by 24 publications

References 45 publications

Cosmological Particle Production in Quantum Gravity

Cosmological Particle Production in Quantum Gravity

Quantum Kasner transition in a locally rotationally symmetric Bianchi II universe

Kink-antikink scattering in a quantum vacuum

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