Holographic Thermodynamics of Dyonic Dilaton AdS Black Holes

Abstract

We investigate the holographic dual of the extended bulk thermodynamics of dyonic dilaton AdS black holes by allowing both the cosmological constant and Newton's gravitational constant to vary. In the dual CFT thermodynamics, the central charge $C$ and chemical potential $\mu$ as its conjugate enter the thermodynamic relations, in addition to $(\tilde{T},\tilde{S})$, $(\tilde{Q},\tilde{\Phi})$, $(\tilde{P},\tilde{\Psi})$, $(\tilde{\mathcal{P}},\tilde{V})$. We consider sixteen different ensembles related to those five pairs of thermodynamic variables which we separate into fixed volume and pressure ensembles. Due to the symmetry on ($\tilde{Q},\tilde{P}$), we only need to analyze five ensembles each in fixed volume and pressure ensembles. In the fixed volume ensembles, it is found that the fixed ($\tilde{Q},\tilde{P},\tilde{V},\mu$) and ($\tilde{\Phi},\tilde{P},\tilde{V},\mu$) exhibit a zeroth-order phase transition. Interestingly, the fixed ($\tilde{\Phi},\tilde{\Psi},\tilde{V},C$) ensemble shows the zeroth- and first-order phase transitions at above and below critical potential $\tilde{\Upsilon}_c$, respectively. In the fixed pressure ensembles, it is found that richer structures appear where the sign of $\mu$ heavily influences phase space for several ensembles. For fixed ($\tilde{Q},\tilde{P},\tilde{\mathcal{P}},\mu$) and ($\tilde{\Phi},\tilde{P},\tilde{\mathcal{P}},\mu$), they show the zeroth-, first-, and second-order phase transitions. For the fixed ($\tilde{\Phi},\tilde{\Psi},\tilde{\mathcal{P}},\mu$) ensemble, there is only a zeroth-order phase transition occurs. The other ensembles which we do not mention eventually do not show any phase transition. These findings provide deeper insight into how bulk gravitational variations, particularly regarding the cosmological and gravitational constants, translate to exact critical phenomena and richer phase structures within CFT.