Absract:
We study black hole thermodynamics using two-dimensional dilaton gravity obtained by spherical reduction of four-dimensional Einstein–Maxwell theory. Its nonlinear potential reproduces the Hawking–Page and small/large Reissner–Nordström–AdS black hole transitions, capturing non-extremal thermodynamics beyond the Jackiw–Teitelboim regime. Integrating out electromagnetic massive Kaluza–Klein modes yields local one-loop corrections that shift the entropy and effective charge parameter while preserving the qualitative phase structure. We also discuss how the lightest massive Maxwell Kaluza-Klein modes modify the SO(3) graviphoton kinetic term through mixing induced by the background electric flux. The resulting charge-dependent tree-level correction is not parametrically suppressed in the near-extremal limit. This talk is based on arXiv:2606.14016 (accepted for publication in JHEP) and 261029086.