Abstract
We propose a three-dimensional counterpart for Jackiw–Teitelboim gravity coupled to a two-dimensional CFT bath based on partial reduction. Transverse brane fluctuations become the dilaton field, and the island and defect-extremal-surface entropies agree in the construction.
Context
JT gravity coupled to a bath is a central model for semiclassical black-hole evaporation. A higher-dimensional origin clarifies how its gravitational and field-theory sectors are assembled.
Main result
The transverse displacement of a defect brane becomes the dilaton under partial reduction, reproducing the full JT action and the same fine-grained entropy as the defect-extremal-surface calculation.
Why it matters
It provides a Lorentzian higher-dimensional realization of JT gravity coupled to a bath and makes the relation between two entropy prescriptions explicit.
Citation / BibTeX
@article{Deng:2023JTPartialReduction,
author = {Deng, Feiyu and An, Yu-Sen and Zhou, Yang},
title = {JT gravity from partial reduction and defect extremal surface},
journal = {JHEP},
volume = {02},
pages = {219},
year = {2023},
doi = {10.1007/JHEP02(2023)219},
eprint = {2206.09609},
archivePrefix = {arXiv}
}