Unimodular JT gravity and de Sitter quantum cosmology

Fuente: arXiv
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Main Authors: Alexandre, Bruno, Etkin, Altay, Rassouli, Farbod-Sayyed
Format: Preprint
Published: 2025
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author Alexandre, Bruno
Etkin, Altay
Rassouli, Farbod-Sayyed
author_facet Alexandre, Bruno
Etkin, Altay
Rassouli, Farbod-Sayyed
contents In this work, we show that a gauge-theoretic description of Jackiw-Teitelboim (JT) gravity naturally yields a Henneaux-Teitelboim (HT) unimodular gravity via a central extension of its isometry group, valid for both flat and curved two-dimensional spacetimes. HT gravity introduces a unimodular time canonically conjugate to the cosmological constant, serving as a physical time in quantum cosmology. By studying the mini-superspace reduction of $\text{HT}_2$ gravity, the Wheeler-DeWitt equation becomes a Schrödinger-like equation, giving a consistent and unitary quantum theory. Analysis of the wavefunction's probability density reveals a quantum distribution for the scale factor $a$, offering a quantum perspective on the expansion and contraction of the universe. In this perspective, the possibility of reaching the singular point $a=0$ signals that topology change could occur. Finally, we give a consistent quantum description of unimodular time that aligns seamlessly with Page-Wootters formulation of quantum mechanics, where quantum correlations between unimodular time and JT gravity are studied in $\text{HT}_2$ quantum cosmology.
format Preprint
id arxiv_https___arxiv_org_abs_2501_17213
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Unimodular JT gravity and de Sitter quantum cosmology
Alexandre, Bruno
Etkin, Altay
Rassouli, Farbod-Sayyed
General Relativity and Quantum Cosmology
High Energy Physics - Theory
In this work, we show that a gauge-theoretic description of Jackiw-Teitelboim (JT) gravity naturally yields a Henneaux-Teitelboim (HT) unimodular gravity via a central extension of its isometry group, valid for both flat and curved two-dimensional spacetimes. HT gravity introduces a unimodular time canonically conjugate to the cosmological constant, serving as a physical time in quantum cosmology. By studying the mini-superspace reduction of $\text{HT}_2$ gravity, the Wheeler-DeWitt equation becomes a Schrödinger-like equation, giving a consistent and unitary quantum theory. Analysis of the wavefunction's probability density reveals a quantum distribution for the scale factor $a$, offering a quantum perspective on the expansion and contraction of the universe. In this perspective, the possibility of reaching the singular point $a=0$ signals that topology change could occur. Finally, we give a consistent quantum description of unimodular time that aligns seamlessly with Page-Wootters formulation of quantum mechanics, where quantum correlations between unimodular time and JT gravity are studied in $\text{HT}_2$ quantum cosmology.
title Unimodular JT gravity and de Sitter quantum cosmology
topic General Relativity and Quantum Cosmology
High Energy Physics - Theory
url https://arxiv.org/abs/2501.17213