arXiv subjects

Prabwal Phukon

Publications and source records attributed to Prabwal Phukon.

51 records · Page 3Linked to original sources

arXiv2024

Thermodynamic topology of topological charged dilatonic black holes

The aim of this paper is to explore the thermodynamic topology of topological charged dilatonic black holes. To achieve this, our study will begin by examining the characteristics of topological charged black holes in dilaton gravity. Specifically, we will concentrate on the impact of the topological constant on the event horizon of these black holes. Subsequently, we will analyze these black holes, considering their thermodynamic and conserved quantities, in order to assess the validity of the first law of thermodynamics. We explore the thermodynamic topology of these black holes by treating them as thermodynamic defects. For our study, we examine two types of thermodynamic ensembles: the fixed $q$ ensemble and the fixed $ϕ$ ensemble. To study the impact of the topological constant ($% k$) on thermodynamic topology, we consider all possible types of curvature hypersurfaces that can form in these black holes. By calculating the topological charges at the defects within their thermodynamic spaces, we analyze both the local and global topology of these black holes. We also investigate how the parameters of dilaton gravity affect the thermodynamic topology of black holes and highlight the differences compared to charged black holes in the General Relativity.

hep-th↗

arXiv2024

Restricted Phase Space Thermodynamics of Dyonic AdS Black Holes: Comparative Analysis Using Different Entropy Models

We study the Restricted Phase Space Thermodynamics (RPST) for the AdS dyonic black hole carrying the central charge $C$ and the chemical potential $μ$, neglecting the pressure and conjugate volume along with comparison of different entropy models namely the Bekenstein-Hawking and the Rényi entropy model. Inclusion of the magnetic charge $\tilde{Q}_m$ gives rise to a richer phase structure of the study of thermodynamics by adding a non-equilibrium transition from an unstable small black hole to a stable black hole on top of the Van der Waals transition in the $T-S$ processes and a Hawking-Page transition in the $F-T$ plots. We study an extra mixed ensemble ($\tildeΦ_e,\tilde{Q}_m)$ due to the inclusion of $\tilde{Q}_m$ where we see Van der Waals phase transition and whose plots change as the entropy model changes though the style of transition remains the same. We observe an interesting phenomenon where changing the Rényi parameter $λ$, the $T-S$ process changes the same way as when varying the central charge $C$ underlining some similarity that is not seen in the Bekenstein Hawking entropy model. We observe a similarity between the plots when both charges are turned off relating to the Schwarzschild black hole and the grand-canonical ensemble. One can observe that as the entropy models are changed, the homogeneity is not lost where the mass as a function of extensive variables is of order one and the rest zero. Finally, we see a similarity in the $μ-C$ process across the entropy models signally some universality across entropy models as well as different types of black holes studied before.

hep-th↗

arXiv2024

Thermodynamics and Null Geodesics of a Schwarzschild Black Hole Surrounded by a Dehnen Type Dark Matter Halo

In this work, we derive a novel black hole solution surrounded by a Dehnen-(1,4,0) type dark matter halo by embedding a Schwarzschild black hole within the halo, constituting a composite dark matter-black hole system. The thermodynamics of the resulting effective black hole spacetime is then studied with particular attention to the influence of the dark matter parameters on various thermodynamic properties. We examine the specific heat and free energy to assess the thermodynamic stability of the model. Furthermore, the null geodesics and the effective potential of light rays are studied to investigate how the dark matter parameters affect these geodesics and the radii of circular orbits. The stability of circular null geodesics is analyzed using dynamical systems and Lyapunov exponents, which represents the dynamical behaviour of the circular photon orbits. Finally, we studied if the circular geodesics exhibit chaotic behaviour using the chaos-bound condition.

gr-qc↗

arXiv2024

Restricted Phase Space Thermodynamics of NED-AdS Black Holes

We study the Restricted Phase Space Thermodynamics (RPST) of magnetically charged Anti de Sitter (AdS) black holes sourced by nonlinear electrodynamics(NED). The first law and the corresponding Euler relation are examined using the scaling properties. While the mass is homogeneous in the first order, the intensive variables are observed to follow zeroth order homogeneity. We use numerical and graphical techniques to find the critical points of the various thermodynamic quantities. By utilizing the re-scaling properties of the equation of states, we study the thermodynamic processes using different pairs of variables. From our analysis, we infer that although the RPS thermodynamics of NED-AdS black hole resembles those of RN-AdS, Kerr-AdS, Kerr-Sen-Ads black holes in most of its aspects, hinting at a possible universality, there exists one particular $μ-C$ process that differs in its behaviour from its counterparts in earlier reported works.

hep-th↗

arXiv2024

Lyapunov Exponents and Phase Transition of Hayward AdS Black Hole

In this paper, we study the relationship between the phase transition and Lyapunov exponents for 4D Hayward anti-de Sitter (AdS) black hole. We consider the motion of massless and massive particles around an unstable circular orbit of the Hayward AdS black hole in the equatorial plane and calculate the corresponding Lyapunov exponents. The phase transition is found to be well described by the multivaled Lyapunov exponents. It is also found that different phases of Hayward AdS black hole coincide with different branches of the Lyapunov exponents. We also study the discontinuous change in the Lyapunov exponents and find that it can serve as an order parameter near the critical point. The critical exponent of change in Lyapunov exponent near the critical point is found to be $1/2$.

hep-th↗

arXiv2024

Thermodynamic topology of black Holes in f(R) gravity

In this work, we study the thermodynamic topology of a static, a charged static and a charged, rotating black hole in $f(R)$ gravity. For charged static black holes, we work in two different ensembles: fixed charge$(q)$ ensemble and fixed potential$(ϕ)$ ensemble. For charged, rotating black hole, four different types of ensembles are considered: fixed $(q, J)$, fixed $(ϕ, J)$, fixed $(q,Ω)$ and fixed $(ϕ,Ω)$ ensemble, where $J$ and $Ω$ denotes the angular momentum and the angular frequency respectively. Using the generalized off-shell free energy method, where the black holes are treated as topological defects in their thermodynamic spaces, we investigate the local and global topology of these black holes via the computation of winding numbers at these defects. For static black hole we work in three model. We find that the topological charge for a static black hole is always $-1$ regardless of the values of the thermodynamic parameters and the choice of $f(R)$ model. For a charged static black hole, in the fixed charge ensemble, the topological charge is found to be zero. Contrastingly, in the fixed $ϕ$ ensemble, the topological charge is found to be $-1.$ For charged static black holes, in both the ensembles, the topological charge is observed to be independent of the thermodynamic parameters. For charged, rotating black hole, in fixed $(q, J)$ ensemble, the topological charge is found to be $1.$ In $(ϕ, J)$ ensemble, we find the topological charge to be $1.$ In case of fixed $(q,Ω)$ ensemble, the topological charge is $1$ or $0$ depending on the value of the scalar curvature($R$). In fixed $(Ω,ϕ)$ ensemble, the topological charge is $-1,0$ or $1$ depending on the values of $R,Ω$ and $ϕ.$

hep-th↗

arXiv2023

Thermodynamic topology of 4D Euler-Heisenberg-AdS black hole in different ensembles

We study the thermodynamic topology of 4D Euler-Heisenberg-AdS (EHAdS) black hole and higher-order QED corrected Euler-Heisenberg-AdS black hole in different ensembles using generalized off-shell free energy. In this approach, black holes are viewed as defects in the thermodynamic space. We work in two ensembles: canonical ensemble in which the charge is kept fixed and grand canonical ensemble in which the conjugate potential $ϕ_e$ is kept fixed. In each case, the local and global topology of the thermodynamic space is investigated via the computation of winding numbers at the defects. For 4D Euler-Heisenberg-AdS black hole in canonical ensemble, the topological class is found to be different depending on the Euler-Heisenberg (EH) parameter $a$. The topological numbers for $a<0$ and $a>0$ cases are found to be $W=+1$ and $W=0$ respectively. The topological number is found to be independent of the variation in pressure $P$ and charge $Q$ of the black hole. With the introduction of higher order QED correction, the difference in the topological class of 4D EHAdS black hole with the sign of $a$ is observed to go away.The topological number in this case is found to be $W=+1$ irrespective of the values of $a$, $P$ and $Q$. In the grand canonical ensemble, the topological number for both EHAdS and higher order QED corrected EHAdS black hole is found to be $W=0$, independent of the values of $P$, $ϕ_e$ and $a$. Therefore, we infer that the topological class of both 4D EHAdS black hole and higher order QED corrected EHAdS black hole is ensemble dependent. Moreover, in the canonical ensemble, higher order QED correction alters the topological class of the black hole for positive values of EH parameter $a$. In the grand canonical ensemble, the higher order corrections do not change the thermodynamic topology of the black hole.

hep-th↗

arXiv2023

Thermodynamic Topology of $D=4,5$ Horava Lifshitz Black Hole in Two Ensembles

We study the thermodynamic topology of four and five dimensional Horava Lifshitz (HL) black holes in Horava gravity. These exotic black hole solutions belong to a special class of of black holes whose thermodynamics exhibit a line of (continuous) second order phase transitions known as $λ$ phase transitions akin to those observed in the superfluidity of liquid $^{4}He$. To analyze their thermodynamic topology, we treat the Horava Lifshitz (HL) black holes as topological defects in their thermodynamic spaces and compute the winding numbers at those defects. We work in two different ensembles: fixed $ε$ ensemble and fixed $ζ$ ensemble, where $ε$ is a parameter of the HL black holes and $ζ$ is its conjugate parameter. In the fixed $ε$ ensemble, three different horizon types are considered : the spherical horizon for $k=+1$, the flat horizon for $k=0$, and the hyperbolic horizon for $k=-1$. In the fixed $ζ$ ensemble, two different horizon types are considered : the spherical horizon for $k=+1$, and the hyperbolic horizon for $k=-1$.

hep-th↗

arXiv2023

Thermodynamic topology of 4D Dyonic AdS black holes in different ensembles

We study the thermodynamic topology of four dimensional dyonic Anti-de-Sitter(AdS) black hole in three different ensembles: canonical, mixed and grand canonical ensemble. While canonical ensemble refers to the ensemble with fixed electric and magnetic charges, mixed ensemble is an ensemble where we fix magnetic charge and electric potential. In the grand canonical ensemble, potentials corresponding to both electric and magnetic charges are kept fixed. In each of these ensembles, we first compute the topological charges associated with critical points. We find that while in both canonical and mixed ensembles, there exists one conventional critical point with topological charge $-1$, in the grand canonical ensemble, we find no critical point. Then, we consider the dyonic AdS black hole as topological defects in thermodynamic space and study its local and global topology by computing the winding numbers at the defects. We observe that while the topologies of the black hole in canonical and mixed ensembles are identical with total topological charge equaling $1$, in the grand canonical ensemble, depending on the values of potentials, the total topological charge is either equal to $0$ or $1$. In canonical and mixed ensembles, either one generation and one annihilation points or no generation/annihilation points are found. In the grand canonical ensemble, depending on the values of potentials, we find either one generation point or no generation/annihilation point. Thus, we infer that the topological class of $4$D dyonic AdS black hole is ensemble dependent.

hep-th↗

arXiv2014

Generalized Superconductors and Holographic Optics

We study generalized holographic s-wave superconductors in four dimensional R-charged black hole and Lifshitz black hole backgrounds, in the probe limit. We first establish the superconducting nature of the boundary theories, and then study their optical properties. Numerical analysis indicates that a negative Depine-Lakhtakia index may appear at low frequencies in the theory dual to the R-charged black hole, for certain temperature ranges, for specific values of the charge parameter. The corresponding cut-off values for these are numerically established in several cases. Such effects are seen to be absent in the Lifshitz background where this index is always positive.

hep-th↗

arXiv2014

R-Charged Black Holes and Holographic Optics

We analyze momentum dependent vector modes in the context of gauge theories dual to R-charged black holes in $D=4$, $5$ and $7$. For a variety of examples, the master variables are constructed, for which the linearized equations for the perturbations decouple. These allow for the computation of momentum dependent correlation functions. Away from the hydrodynamic limit, numerical analysis using the decoupled equations of motion is used to obtain the analogues of the Depine-Lakhtakia (DL) index. For specified ranges of frequencies, a negative index of refraction is seen to occur in all cases.

hep-th↗

arXiv2012

Geodesics in Information Geometry : Classical and Quantum Phase Transitions

We study geodesics on the parameter manifold, for systems exhibiting second order classical and quantum phase transitions. The coupled non-linear geodesic equations are solved numerically for a variety of models which show such phase transitions, in the thermodynamic limit. It is established that both in the classical as well as in the quantum case, geodesics are confined to a single phase, and exhibit turning behavior near critical points. Our results are indicative of a geometric universality in widely different physical systems.

cond-mat.stat-mech↗

arXiv2011

Directed Random Walks on Colored, Periodic Lattices: A Gauge Theoretic Approach

We define a random walk problem which admits analytic results, on a class of infinite periodic lattices which are directed and colored. Our approach is motivated from the fact that such lattices arise in string theoretic constructs of certain gauge theories. An operator counting problem in the latter is mapped to a problem in random walks. This is illustrated with several examples.

cond-mat.stat-mech↗

arXiv2011

On the Higgsing and UnHiggsing of Fano 3-Folds

We study the Higgsing and UnHiggsing of M2-brane theories that probe cones over smooth toric Fano 3-folds, via brane tilings. We find many new examples of M2-brane gauge theories not studied previously in the literature, including those that do not correspond to cones over Fano varieties. Our analysis also provides, upon unHiggsing the known Fano varieties, new examples of quiver gauge theories that describe the same toric variety, but with external point multiplicities. As a byproduct of our results, we discuss an example of a CY 4-fold that does not have a tiling description, and study the Higgsing of this theory.

hep-th↗

arXiv2011

On Black Hole Entropy Corrections in the Grand Canonical Ensemble

We study entropy corrections due to thermal fluctuations for asymptotically AdS black holes in the grand canonical ensemble. To leading order, these can be expressed in terms of the black hole response coefficients via fluctuation moments. We also analyze entropy corrections due to mass and charge fluctuations of R-charged black holes, and our results indicate an universality in the logarithmic corrections to charged AdS black hole entropy in various dimensions.

hep-th↗