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arXiv · 2607.06826

BMS$_3$ invariant field theories

Diego Hidalgo·Stefan Vandoren·Huaxuan Zeng
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Abstract

We review existing and construct new two-dimensional field theories that exhibit BMS$_3$ symmetry, with and without central extensions. These include interacting electric, magnetic and canonical BMS$_3$ scalar theories, as well as couplings between the electric and magnetic sectors. We provide a careful analysis of boundary contributions at the corner points $u\rightarrow\pm\infty$, determine the counterterms and boundary conditions required by BMS$_3$ invariance, and study the corresponding variational principles. Furthermore, we introduce external sources and derive the associated flux-balance laws. Within the framework of flat-space holography, we show that a simple free electric BMS$_3$ model with the appropriate central charge reproduces the monodromy classification of three-dimensional Einstein gravity. Finally, we investigate the flat-space limits of both AdS$_3$ and dS$_3$, whose boundary dynamics are described by Carrollian limits of Liouville and Euclidean Liouville theory, respectively. Although the resulting BMS$_3$ theories possess isomorphic spectra, they differ in the signs of the supertranslation charges and the central charge. This suggests that the flat-space limits of AdS$_3$ and dS$_3$ provide complementary realizations of flat-space holography.

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Diego Hidalgo, Stefan Vandoren, Huaxuan Zeng. 2026-07-07. BMS$_3$ invariant field theories. https://arxiv.org/abs/2607.06826

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