I will discuss how the central charges appearing in near-horizon symmetry algebras arise from an anomalous transformation of the null boundary term in the gravitational action. This parallels the way in which the holographic Weyl anomaly appears in AdS/CFT, with the ambiguity in the normalization of the null generator being the analogue of the choice of Weyl frame. As an application, I will analyze a generalization of the near-horizon Virasoro symmetries of Haco, Hawking, Perry, and Strominger, and give a systematic derivation of the Wald-Zoupas fluxes and central charges. In particular, I will discuss a way to define the quasilocal charges unambiguously, and show that the central charge computed by the charge algebra is directly related to the horizon entropy via the Cardy formula.
Based on https://arxiv.org/abs/2009.10739 and https://arxiv.org/abs/2006.02430