Spikes and spines in 3D Lorentzian simplicial quantum gravity

Fuente: arXiv
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Hauptverfasser: Borissova, Johanna, Dittrich, Bianca, Qu, Dongxue, Schiffer, Marc
Format: Preprint
Veröffentlicht: 2024
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author Borissova, Johanna
Dittrich, Bianca
Qu, Dongxue
Schiffer, Marc
author_facet Borissova, Johanna
Dittrich, Bianca
Qu, Dongxue
Schiffer, Marc
contents Simplicial approaches to quantum gravity such as Quantum Regge Calculus and Spin Foams include configurations where bulk edges can become arbitrarily large while keeping the lengths of the boundary edges small. Such configurations pose significant challenges in Euclidean Quantum Regge Calculus, as they lead to infinities for the partition function and length expectation values. Here we investigate such configurations in three-dimensional Lorentzian Quantum Regge Calculus, and find that the partition function and length expectation values remain finite. This shows that the Lorentzian approach can avoid a key issue of the Euclidean approach. We also find that the space of configurations, for which bulk edges can become very large, is much richer than in the Euclidean case. In particular, it includes configurations with irregular light-cone structures, which lead to imaginary terms in the Regge action and branch cuts along the Lorentzian path integral contour. Hence, to meaningfully define the Lorentzian Regge path integral, one needs to clarify how such configurations should be handled.
format Preprint
id arxiv_https___arxiv_org_abs_2406_19169
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Spikes and spines in 3D Lorentzian simplicial quantum gravity
Borissova, Johanna
Dittrich, Bianca
Qu, Dongxue
Schiffer, Marc
General Relativity and Quantum Cosmology
High Energy Physics - Theory
Simplicial approaches to quantum gravity such as Quantum Regge Calculus and Spin Foams include configurations where bulk edges can become arbitrarily large while keeping the lengths of the boundary edges small. Such configurations pose significant challenges in Euclidean Quantum Regge Calculus, as they lead to infinities for the partition function and length expectation values. Here we investigate such configurations in three-dimensional Lorentzian Quantum Regge Calculus, and find that the partition function and length expectation values remain finite. This shows that the Lorentzian approach can avoid a key issue of the Euclidean approach. We also find that the space of configurations, for which bulk edges can become very large, is much richer than in the Euclidean case. In particular, it includes configurations with irregular light-cone structures, which lead to imaginary terms in the Regge action and branch cuts along the Lorentzian path integral contour. Hence, to meaningfully define the Lorentzian Regge path integral, one needs to clarify how such configurations should be handled.
title Spikes and spines in 3D Lorentzian simplicial quantum gravity
topic General Relativity and Quantum Cosmology
High Energy Physics - Theory
url https://arxiv.org/abs/2406.19169