Unimodular time in JT gravity: a holographic clock

[2601.07911] Unimodular time in JT gravity: a holographic clock Skip to main content Search Submit Donate Log in High Energy Physics - Theory arXiv:2601.07911 (hep-th) [Submitted on 12 Jan 2026] Title: Unimodular time in JT gravity: a holographic clock Authors: Altay Etkin , Farbod-Sayyed Rassouli View PDF HTML (experimental) Abstract: How is a ''bulk clock'' encoded holographically? We address this in Jackiw-Teitelboim (JT) gravity, where a natural physical clock emerges by promoting the vacuum energy to a dynamical variable: the vacuum cosmological constant becomes a top form degree of freedom conjugate to spacetime volume, thereby defining a notion of bulk physical time. This construction is naturally formulated in the Henneaux-Teitelboim (HT) framework. We show that the boundary dynamics is the Schwarzian mode coupled to a free particle on $U(1)$, matching the universal low-energy effective action of the complex SYK model. By further clarifying the role of the vacuum cosmological constant as a top form, we establish the equivalence between JT gravity coupled to two-dimensional Maxwell theory and 2d HT gravity via an explicit field redefinition. The initial question is addressed: we show that the resulting boundary theory can itself be rewritten as an observer action, equivalently a $(0+1)$-dimensional HT theory. This yields a direct identification of the boundary clock with the $U(1)$ phase mode, and makes its relation to the bulk clock explicit. Comments: 42 pages, 3 figures Subjects: High Energy Physics - Theory (hep-th) ; General Relativity and Quantum Cosmology (gr-qc) Cite as: arXiv:2601.07911 [hep-th] (or arXiv:2601.07911v1 [hep-th] for this version) https://doi.org/10.48550/arXiv.2601.07911 Focus to learn more arXiv-issued DOI via DataCite Journal reference: J. High Energ. Phys. 2026, 193 (2026) Related DOI : https://doi.org/10.1007/JHEP08%282026%29193 Focus to learn more DOI(s) linking to related resources Submission history From: Sayyed Farbod Rassouli Mr [ view email ] [v1] Mon, 12 Jan 2026 19:00:01 UTC (72 KB) Full-text links: Access Paper: View PDF HTML (experimental) TeX Source view license Current browse context: hep-th < prev | next > new | recent | 2026-01 Change to browse by: gr-qc References & Citations INSPIRE HEP NASA ADS Google Scholar Semantic Scholar export BibTeX citation Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer ( What is the Explorer? ) Connected Papers Toggle Connected Papers ( What is Connected Papers? ) Litmaps Toggle Litmaps ( What is Litmaps? ) scite.ai Toggle scite Smart Citations ( What are Smart Citations? ) Code, Data, Media Code, Data and Media Associated with this Article alphaXiv Toggle alphaXiv ( What is alphaXiv? ) Links to Code Toggle CatalyzeX Code Finder for Papers ( What is CatalyzeX? ) DagsHub Toggle DagsHub ( What is DagsHub? ) GotitPub Toggle Gotit.pub ( What is GotitPub? ) Huggingface Toggle Hugging Face ( What is Huggingface? ) ScienceCast Toggle ScienceCast ( What is ScienceCast? ) Demos Demos Replicate Toggle Replicate ( What is Replicate? ) Spaces Toggle Hugging Face Spaces ( What is Spaces? ) Spaces Toggle TXYZ.AI ( What is TXYZ.AI? ) Related Papers Recommenders and Search Tools Link to Influence Flower Influence Flower ( What are Influence Flowers? ) Core recommender toggle CORE Recommender ( What is CORE? ) IArxiv recommender toggle IArxiv Recommender ( What is IArxiv? ) Author Venue Institution Topic About arXivLabs arXivLabs: experimental projects with community collaborators arXivLabs is a framework that allows collaborators to develop and share new arXiv features directly on our website. Both individuals and organizations that work with arXivLabs have embraced and accepted our values of openness, community, excellence, and user data privacy. arXiv is committed to these values and only works with partners that adhere to them. Have an idea for a project that will add value for arXiv's community? Learn more about arXivLabs . Which authors of this paper are endorsers? | Disable MathJax ( What is MathJax? ) We gratefully acknowledge support from our major funders , member institutions , and all contributors. About · Help · Contact · Subscribe · Copyright · Privacy · Accessibility · Operational Status (opens in new tab) Major funding support from

Related documents

• Unimodular time in JT gravity: a holographic clock#674278
• Higher-Spin dS/CFT beyond minimal type-A, and the doubled nature of de Sitter space#798234
• Higher-Spin dS/CFT beyond minimal type-A, and the doubled nature of de Sitter space#796821
• dS/CFT Holography including Fermionic Fields#1119146
• New quasidilaton theory in partially constrained vielbein formalism#785342