Work

Thermodynamic volumes of extended black hole thermodynamics with auxiliary gauge fields

Year: 2026

Type: article

Abstract: 2 By applying the Iyer-Wald formalism to the modified Lagrangian form for the gravitational system, where the coupling constants appearing in the original Lagrangian form, such as the cosmological constant, are promoted to the dynamical scalar fields by introducing the corresponding auxiliary gauge fields, we derive the first law of the extended black hole thermodynamics, where the resulting thermodynamic volumes as the conjugate thermodynamic variables to the coupling constants are nevertheless independent of the auxiliary gauge fields and exactly the same as those obtained before via varying the coupling constants by brute force. In addition, it is further shown that such volumes can also be expressed in terms of the auxiliary gauge fields and evaluated on the black hole horizon, validating the proposal made in the previous literature.

Source: Physics Letters B

DOI: 10.1016/j.physletb.2026.141027

Authors: Zili Mou, Yu Tian, Hongbao Zhang

Institutions: Beijing Normal University, Chinese Academy of Sciences, Institute of Theoretical Physics, University of Chinese Academy of Sciences

Language: English

Topic: Black Holes and Theoretical Physics

Subfield: Nuclear and High Energy Physics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: diamond

Funder: National Natural Science Foundation of China

Awards: G4482933530, G5811165953, G6898621578