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arXiv · 2509.09239

Extracting Edge Modes: Reduction of 3D and 2D Gravities

Euihun Joung·Sejin Kim
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Abstract

We investigate the boundary reduction of 3D Einstein gravity and JT gravity into their respective edge mode theories - namely, the Liouville and Alekseev-Shatashvili, and Schwarzian models. By examining the roles of boundary conditions, canonical transformations, and differing formulations - metric versus Chern-Simons - we clarify how physical degrees of freedom become localized at the boundary and resolve several long-standing ambiguities in the reduction procedure.

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Euihun Joung, Sejin Kim. 2025-09-11. Extracting Edge Modes: Reduction of 3D and 2D Gravities. https://doi.org/10.1103/bgjv-m11w

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