Hawking--Page Universality, Thermodynamic Dipoles and Categorical Defects

Abstract

We reconsider the Hawking--Page transition using the common thermodynamic vector field whose zeros include the Davies and Hawking--Page points. In the elementary AdS branch their winding numbers are $w_{\mathrm{D}}=-1$ and $w_{\mathrm{HP}}=+1$, so the pair has zero total charge but a non-zero signed first moment. After normalization by the Davies scales this moment gives the familiar universal ratios $C_S$ and $C_T$; in four dimensions $C_S=2$ and $C_T=2/\sqrt{3}-1$. We check the construction for Schwarzschild--AdS, grand-canonical Reissner--Nordström--AdS, charged non-rotating black holes in arbitrary dimension, and Kerr--AdS at fixed angular velocity. The same reduced geometry gives a barrier $B=1/3$ in four dimensions and $B(d)=1/[(d-1)(d-3)]$. Finally we propose a formulation involving a defect-resolved version for categorical or non-invertible symmetry sectors.