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Extended Black Hole Thermodynamics from Extended Iyer-Wald Formalism
Yong Xiao1,2, Yu Tian3,4, Yu-Xiao Liu5
1Key Laboratory of High-precision Computation and Application of Quantum Field Theory of Hebei Province, College of Physical Science and Technology, Hebei University, Baoding 071002, China.
Abstract:
In recent years, there has been significant interest in the field of extended black hole thermodynamics, where the cosmological constant and/or other coupling parameters are treated as thermodynamic variables. Drawing inspiration from the Iyer-Wald formalism, which reveals the intrinsic and universal structure of conventional black hole thermodynamics, we illustrate that a proper extension of this formalism also unveils the underlying theoretical structure of extended black hole thermodynamics. As a remarkable consequence, for any gravitational theory described by a diffeomorphism invariant action, it is always possible to construct a consistent extended thermodynamics using this extended formalism.
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