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Lorentzian Quantum Cosmology

Feldbrugge, J., Lehners, J.-L., & Turok, N. (2017). Lorentzian Quantum Cosmology. Physical Review D, 95: 103508. doi:10.1103/PhysRevD.95.103508.

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Genre: Journal Article

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1703.02076.pdf (Preprint), 4MB
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PRD.95.103508.pdf (Publisher version), 644KB

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### Creators

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Creators:
Feldbrugge, Job, Author
Lehners, Jean-Luc1, Author
Turok, Neil, Author
Affiliations:
1String Cosmology, AEI-Golm, MPI for Gravitational Physics, Max Planck Society, ou_1753351

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Free keywords: High Energy Physics - Theory, hep-th,General Relativity and Quantum Cosmology, gr-qc
Abstract: We argue that the Lorentzian path integral is a better starting point for quantum cosmology than the Euclidean version. In particular, we revisit the mini-superspace calculation of the Feynman path integral for quantum gravity with a positive cosmological constant. Instead of rotating to Euclidean time, we deform the contour of integration over metrics into the complex plane, exploiting Picard-Lefschetz theory to transform the path integral from a conditionally convergent integral into an absolutely convergent one. We show that this procedure unambiguously determines which semiclassical saddle point solutions are relevant to the quantum mechanical amplitude. Imposing "no-boundary" initial conditions, i.e., restricting attention to regular, complex metrics with no initial boundary, we find that the dominant saddle contributes a semiclassical exponential factor which is precisely the {\it inverse} of the famous Hartle-Hawking result.

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Dates: 2017-03-062017
Publication Status: Published in print
Pages: 44 pages, 8 figures
Publishing info: -
Rev. Method: -
Identifiers: arXiv: 1703.02076
URI: http://arxiv.org/abs/1703.02076
DOI: 10.1103/PhysRevD.95.103508
Degree: -

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### Source 1

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Title: Physical Review D
Other : Phys. Rev. D.
Source Genre: Journal
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Publ. Info: Lancaster, Pa. : American Physical Society
Pages: - Volume / Issue: 95 Sequence Number: 103508 Start / End Page: - Identifier: ISSN: 0556-2821
CoNE: https://pure.mpg.de/cone/journals/resource/111088197762258