Hartle-Hawking No-boundary Proposal and Hořava-Lifshitz Gravity

Fuente: arXiv
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Autores principales: Matsui, Hiroki, Mukohyama, Shinji
Formato: Preprint
Publicado: 2023
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author Matsui, Hiroki
Mukohyama, Shinji
author_facet Matsui, Hiroki
Mukohyama, Shinji
contents We study the Hartle-Hawking no-boundary proposal in the framework of Hořava-Lifshitz gravity. The former is a prominent hypothesis that describes the quantum creation of the universe, while the latter is a potential theory of quantum gravity that ensures renormalizability and unitarity, at least in the so-called projectable version. For simplicity, we focus on a global universe composed of a set of local universes each of which is closed, homogeneous and isotropic. Although applying the no-boundary proposal to Hořava-Lifshitz gravity is not straightforward, we demonstrate that the proposal can be formulated within the Hořava-Lifshitz gravity utilizing the Lorentzian path integral formulation of quantum gravity. In projectable Hořava-Lifshitz gravity, the no-boundary wave function of the global universe inevitably contains entanglement between different local universes induced by ``dark matter as integration constant''. On the other hand, in the non-projectable version, the no-boundary wave function of the global universe is simply the direct product of wave functions of each local universe. We then discuss how the no-boundary wave function is formulated under Dirichlet and Robin boundary conditions. For the Dirichlet boundary condition, we point out that its on-shell action diverges due to higher-dimensional operators, but this problem can in principle be ameliorated by taking into account the renormalization group flow. However, utilizing the Picard-Lefschetz theory to identify the relevant critical points and performing the complex lapse integration, we find that only the tunneling wave function can be obtained, as in the case of general relativity. On the other hand, for the Robin boundary condition with a particular imaginary Hubble expansion rate at the initial hypersurface, the no-boundary wave function can be achieved in the Hořava-Lifshitz gravity.
format Preprint
id arxiv_https___arxiv_org_abs_2310_00210
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Hartle-Hawking No-boundary Proposal and Hořava-Lifshitz Gravity
Matsui, Hiroki
Mukohyama, Shinji
General Relativity and Quantum Cosmology
Cosmology and Nongalactic Astrophysics
High Energy Physics - Theory
We study the Hartle-Hawking no-boundary proposal in the framework of Hořava-Lifshitz gravity. The former is a prominent hypothesis that describes the quantum creation of the universe, while the latter is a potential theory of quantum gravity that ensures renormalizability and unitarity, at least in the so-called projectable version. For simplicity, we focus on a global universe composed of a set of local universes each of which is closed, homogeneous and isotropic. Although applying the no-boundary proposal to Hořava-Lifshitz gravity is not straightforward, we demonstrate that the proposal can be formulated within the Hořava-Lifshitz gravity utilizing the Lorentzian path integral formulation of quantum gravity. In projectable Hořava-Lifshitz gravity, the no-boundary wave function of the global universe inevitably contains entanglement between different local universes induced by ``dark matter as integration constant''. On the other hand, in the non-projectable version, the no-boundary wave function of the global universe is simply the direct product of wave functions of each local universe. We then discuss how the no-boundary wave function is formulated under Dirichlet and Robin boundary conditions. For the Dirichlet boundary condition, we point out that its on-shell action diverges due to higher-dimensional operators, but this problem can in principle be ameliorated by taking into account the renormalization group flow. However, utilizing the Picard-Lefschetz theory to identify the relevant critical points and performing the complex lapse integration, we find that only the tunneling wave function can be obtained, as in the case of general relativity. On the other hand, for the Robin boundary condition with a particular imaginary Hubble expansion rate at the initial hypersurface, the no-boundary wave function can be achieved in the Hořava-Lifshitz gravity.
title Hartle-Hawking No-boundary Proposal and Hořava-Lifshitz Gravity
topic General Relativity and Quantum Cosmology
Cosmology and Nongalactic Astrophysics
High Energy Physics - Theory
url https://arxiv.org/abs/2310.00210