Eur. Phys. J. C, 85, 423 (2025)
Thermodynamics of the Kerr-AdS black hole from an ensemble-averaged theory
Peng Cheng1,*, Jindong Pan2, Haichen Xu2 and Si-Jiang Yang3
1 Center for Joint Quantum Studies and Department of Physics, Tianjin University, 300350 Tianjin, People’s Republic of China.
2 Institute for Theoretical Physics, University of Amsterdam, 1090 GL Amsterdam, The Netherlands.
3 Lanzhou Center for Theoretical Physics, Key Laboratory of Theoretical Physics of Gansu Province, and Key Laboratory of Quantum Theory and Applications of MoE, Lanzhou University, Lanzhou 730000, Gansu, China.
* p.cheng.nl@outlook.com
Abstract
Exploring the universal structure of the gravitational path integral beyond semi-classical saddles and uncovering a compelling statistical interpretation of black hole thermodynamics have long been significant challenges. We investigate the statistical interpretation of the Kerr-AdS black hole thermodynamics through an ensemble-averaged theory. By extending the phase space to include all possible states with conical singularities in their Euclidean counterparts, we derive the probability distribution of different states inherited from the Euclidean gravitational path integral. Moreover, we can define a density matrix of all states in the phase space. By ensemble-averaging over all states, we show that the black hole phase transition naturally arises in the semi-classical limit. Away from the semi-classical regime, the ensemble-averaged theory exhibits a notable deviation from the conventional phase transition. Expanding around the classical saddles yields the subleading-order correction to the Gibbs free energy, which is half of the Hawking temperature. We demonstrate that the half Hawking temperature correction is a universal feature inherent to black holes in asymptotically AdS spacetime. With the subleading-order correction to Gibbs free energy, we also suggest that the whole black hole thermodynamic should be corrected accordingly.
