arXiv subjects

Mehdi Sadeghi

Publications and source records attributed to Mehdi Sadeghi.

At least 19 recordsLinked to original sources

arXiv2026

$T\bar{T}$ deformation and multiple-flavor Lorentzian threads

This work is motivated by the proposed relationship among finite cut-off holography and generalized $T\bar T$ deformations, and examines holographic complexity within the framework of the "complexity = anything" proposal. Employing a Fefferman-Graham expansion near the finite cut-off surface, the deformation-induced correction to generalized complexity is derived and shown to allow a systematic expansion in terms of generalized Willmore-type functionals. The resulting formulation broadens earlier findings for the complexity-volume proposal to encompass arbitrary geometric complexity measures. Furthermore, the structure of the correction allows a natural interpretation as multiple-flavor Lorentzian threads, where distinct thread sectors correspond to different curvature invariants in the complexity functional. These results show a geometric connection among finite cut-off holography, generalized complexity, and the emergence of non-local computational structures in holographic quantum field theories.

hep-th↗

arXiv2026

Thermodynamic and Topological Phase Transitions of AdS Black Holes with Nonminimal $F^{\alpha\beta}F^{\gamma\lambda}R_{\alpha\gamma}R_{\beta\lambda}$ Coupling

The conventional and topological phase transitions of a four-dimensional asymptotically AdS black hole with a non-minimal coupling term $F^{\alpha\beta}F^{\gamma\lambda}R_{\alpha\gamma}R_{\beta\lambda}$ are investigated. Using a perturbative approach to first order in the coupling $\epsilon$, the thermodynamic quantities are derived and the first law and Smarr relation are verified. Intriguingly, while the $\epsilon = 0$ limit yields the standard Reissner--Nordstr\"om--AdS black hole belonging to the $W^{1+}$ topological class ($W = +1$), switching on the non-minimal coupling fundamentally transforms the topology to the $W^{0-}$ class ($W = 0$). This transition occurs while the van der Waals-type first-order phase transition survives in the intermediate region, embedded within the overall Hawking--Page pattern, rendering the system a hybrid black hole thermodynamic system. The coupling $\epsilon$ thus acts as a topological deformation parameter that alters the universal classification of the system, despite the perturbative nature of the solution.

hep-th↗

arXiv2026

Hydrodynamics of Nonminimal $F^{(a)\alpha \beta } F^{(a)\gamma \lambda } R_{\alpha \gamma } R_{\beta \lambda }$ AdS Black Brane

We investigate the hydrodynamic properties of a strongly coupled non-Abelian plasma dual to a four-dimensional AdS black brane with a nonminimal coupling of the form $q_2 F^{(a)\alpha\beta}F^{(a)\gamma\lambda}R_{\alpha\gamma}R_{\beta\lambda}$ in the bulk action. This higher-derivative term introduces a direct interaction between the Yang-Mills field strength and the Ricci tensor, leading to corrections beyond the minimal Einstein-Yang-Mills theory. Using a perturbative expansion in the small coupling $q_2$, we construct the black brane solution up to first order and employ the fluid-gravity correspondence to compute two key transport coefficients: the DC color conductivity $\sigma$ and the shear viscosity to entropy density ratio $\eta/s$. In holography, $\eta/s$ is inversely proportional to the square of the coupling constant of the boundary theory, while $\sigma$ in Einstein-Maxwell theory satisfies a universal lower bound $\sigma \ge 1$ (in units where $\hbar=1$), saturated for uncharged black holes and characterizing a perfect quantum critical fluid. Our results reveal that the nonminimal coupling significantly alters these transport quantities. For the DC conductivity, we find $\sigma = 1 - q_2 \bigl(9\kappa Q^2/(L^2 r_h^4) + 7\kappa^2 Q^4/(4 r_h^8)\bigr)$, indicating a violation of the conductivity bound for $q_2>0$ while the bound is preserved for $q_2<0$. For the shear viscosity, we obtain $\eta/s = (1/(4\pi))\bigl(1 + q_2\, 7\kappa^2 Q^4/(2 r_h^8)\bigr)$, showing that the KSS bound is modified by a term linear in $q_2$. The sign of $q_2$ determines whether the ratio increases above or decreases below the universal value $1/(4\pi)$. These findings highlight the sensitivity of holographic transport to curvature-coupled gauge interactions and provide a controlled example of how higher-derivative corrections influence the hydrodynamic regime of strongly coupled plasmas.

hep-th↗

arXiv2026

Thermodynamic Topology of 4D Charged AdS Black Holes with $F^{\alpha\beta}F^{\gamma\lambda}R_{\alpha\gamma\beta\lambda}$ Coupling

We investigate the thermodynamic phase transitions of a four-dimensional charged anti-de Sitter black hole endowed with a non-minimal coupling of the form $F^{\alpha\beta}F^{\gamma\lambda}R_{\alpha\gamma\beta\lambda}$. Using perturbative methods, we derive a consistent black hole solution and analyze its thermodynamics through both conventional equilibrium techniques and a topological defect classification approach. The system displays van der Waals-like critical behavior, with a swallow-tail structure in the free energy and distinct phase branches. The topological analysis independently confirms the existence of critical points and classifies the system within the universal topological scheme for black hole thermodynamics.

hep-th↗

arXiv2026

Holographic Aspects of Non-minimal $R^3 F^2 $ Black Brane in an EFT Framework

This work investigates a modified theory of gravity where the Einstein-Hilbert action, including a cosmological constant, is non-minimally coupled to a Yang-Mills field via an $R^3 F_{\mu \alpha}^{(a)} F^{(a)\mu \alpha}$ interaction term. We treat this coupling as the leading higher-derivative correction in a low-energy effective field theory (EFT) deformation of the standard Einstein-Yang-Mills theory. We derive a black brane solution for this model, accurate to the first order in the EFT coupling parameter $q_2$, and specify the regime of validity $\frac{|q_2|}{L^6} \ll 1$. Using gauge/gravity duality techniques, we then compute two key holographic transport coefficients: the color non-abelian direct current (DC) conductivity and the ratio of shear viscosity to entropy density. Our analysis reveals that both transport coefficients are modified by the non-minimal coupling, with the conductivity bound violated for positive $q_2$ and the Kovtun-Son-Starinets (KSS) bound for shear viscosity violated for negative $q_2$. The results are interpreted within the EFT framework, and possible constraints on the sign of $q_2$ from stability and causality are discussed. In the limit where the non-minimal coupling vanishes, our results consistently reduce to those of the standard Yang-Mills Schwarzschild Anti-de Sitter (AdS) black brane.

hep-th↗

arXiv2025

Topological Classification of a 4D AdS Black Hole with Non-Minimal Maxwell Coupling

We perform a topological classification of the phase structure of a four-dimensional AdS black hole with non-minimal Maxwell coupling. Critical points are treated as topological defects, allowing us to assign a winding number to each black hole branch and compute the global topological invariant W. The system exhibits a duality governed by its Maxwell charge Q: for large Q it falls into the class W = 1, displaying van der Waals-type behavior with a first-order small-large black hole transition. For small Q, it shifts to W = 0, characteristic of a Hawking-Page transition. This topological classification provides a model-independent validation of the conventional thermodynamic analysis. Crucially, we find that the non-minimal coupling lambda stabilizes the Hawking-Page universality class W=0 for black holes with non-zero charge, a phenomenon absent in the standard Reissner-Nordstrom-AdS case. This establishes a direct link between the microscopic coupling and the macroscopic topological class, demonstrating the power of topological methods in decoding thermodynamic universality across modified gravity theories.

hep-th↗

arXiv2025

Viscosity of $R^2$ Modified AdS Black Brane

We investigate the Einstein-Hilbert black brane solution in four-dimensional Anti-de Sitter (AdS) spacetime supplemented by a quadratic Ricci scalar term $q L^2 R^2$, where $q$ is a dimensionless coupling constant and $L$ is the AdS radius. The shear viscosity to entropy density ratio, $\frac{\eta}{s}$, is calculated holographically, and deviations from the universal Kovtun-Son-Starinets (KSS) bound are analyzed. Our results indicate that $\frac{\eta}{s} = \frac{1}{4\pi}(1 - 24q)$, demonstrating that the ratio falls below the conjectured lower limit for positive $q$, while it respects the bound for negative $q$. We confirm that our solutions smoothly reduce to the standard Einstein-Hilbert case when $q \to 0$, consistent with expectations. The physical implications of violating the KSS bound are discussed in depth, particularly regarding stability, causality, and the strongly coupled nature of the dual field theory. These findings provide valuable insights into the influence of higher curvature terms on holographic transport properties.

hep-th↗

arXiv2025

Complexity of Einstein-Maxwell-non-minimal coupling $R^2F^2$: the role of the penalty factor

We investigate holographic complexity in Einstein-Maxwell theory with a non-minimal coupling of the form $R^2F_{\mu\nu}F^{\mu\nu}$ within the complexity=anything framework. A perturbative AdS black brane solution is constructed to first order in the non-minimal coupling parameter. Owing to the linear temperature dependence of the resistivity, this model provides a holographic realization of strange metal behavior. The complexity growth rate (CGR) is governed by three independent parameters: the conserved charge, the non-minimal coupling, and the choice of the generalized term entering the complexity functional. We consider three representative generalizations, namely the Weyl tensor squared, $R^2F^2$ , and $F^2$. We provide a physical interpretation of these parameters, the generalized bulk functional analytically induces a deformation of the effective cost metric, which can be interpreted as a bulk penalty factor, while the conserved charge and the non-minimal coupling control an effective scrambling time in the dual theory. The role of the generalization parameter is shown to be closely tied to the structure of the corresponding quantum circuit.

hep-th↗

arXiv2025

Callan-Symanzik-like equation in information theory

Within the "complexity=anything" proposal of holography, the complexity growth rate (CGR) can exhibit jumps, interpreted as phase transitions. We demonstrate that the location and amplitude of these jumps are governed by the dynamics of bulk fields, which, via the fluid-gravity correspondence, map to the boundary energy-momentum tensor. The behavior of the CGR near these critical points exhibits scaling and universality. We show that the CGR satisfies a Callan-Symanzik-like equation near the transitions. Our results provide a new information-theoretic interpretation of the Callan-Symanzik equation, with the CGR running with the energy scale.

quant-ph↗

arXiv2025

A theoretical framework to explain non-Nash equilibrium strategic behavior in experimental games

Conventional game theory assumes that players are perfectly rational. In a realistic situation, however, players are rarely perfectly rational. This bounded rationality is one of the main reasons why the predictions of Nash equilibrium in normative game theory often diverge from human behavior in real experiments. Motivated by the Boltzmann weight formalism, here we present a theoretical framework to predict the non-Nash equilibrium probabilities of possible outcomes in strategic games by focusing on the differences in expected payoffs of players rather than traditional utility metrics. In this model, bounded rationality is parameterized by assigning a temperature to each player, reflecting their level of rationality by interpolating between two decision-making regimes, i.e., utility maximization and equiprobable choices. Our framework predicts all possible joint strategies and is able to determine the relative probabilities for multiple pure or mixed strategy equilibria. To validate model predictions, by analyzing experimental data we demonstrated that our model can successfully explain non-Nash equilibrium strategic behavior in experimental games. Our approach reinterprets the concept of temperature in game theory, leveraging the development of theoretical frameworks to bridge the gap between the predictions of normative game theory and the results of behavioral experiments.

physics.soc-ph↗

arXiv2024

Information, entropy and the paradox of choice: A model for understanding human choice behavior

Choice overload occurs when individuals feel overwhelmed by excessive alternatives during decision making. Although larger choice sets are often assumed to be more satisfying, behavioral evidence reveals an inverted U-shaped relationship between satisfaction and choice set size. However, quantitative frameworks linking information processing to choice satisfaction remain underdeveloped. Here, we develop a simple framework based on relative entropy and effective information to explain this behavior. We propose that satisfaction depends on the probability of finding an ideal option within a choice set and is determined by the informational structure of preferential choice probabilities relative to a baseline state of indifference. Small to moderately sized sets allow efficient comparison and identification of preferred options, thereby maximizing both effective information and satisfaction. As the number of alternatives increases, cognitive limitations increase uncertainty, leading to reduced effective information and satisfaction. This mechanism naturally produces the experimentally observed inverted U-shaped dependence of satisfaction on choice set size. Behavioral experiments across varying choice set sizes closely matched model predictions, suggesting that effective information provides a robust metric for choice satisfaction. These findings offer a principled theoretical account of the paradox of choice and carry broader implications for consumer psychology and human choice behavior.

physics.soc-ph↗

arXiv2024

Thermodynamic Behavior of a 4D Nonminimal Maxwell-AdS Black Hole

In this paper, we derive a black hole solution within the Einstein Maxwell framework incorporating a nonminimal coupling between the Ricci tensor and the Maxwell field strength tensor, using a perturbative approach. We subsequently explore the thermodynamic phase transitions of the black hole in an extended phase space, analyzing both canonical and grand canonical ensembles. Our findings reveal that the system exhibits Van der Waals like behavior in both ensembles. Moreover, for sufficiently small values of electric charge and Maxwell potential, the thermodynamics is dominated by a Hawking Page phase transition.

hep-th↗

arXiv2024

Nonlinear Yang-Mills AdS black brane and DC conductivity

In this paper, we examine Einstein-Hilbert gravity featuring a cosmological constant and a non-abelian nonlinear electromagnetic field that is minimally coupled to gravity. We first present the black brane solution for this model and subsequently calculate the color non-abelian DC conductivity for this solution using AdS/CFT duality. Our results retrieve the Yang-Mills model in the limit as $q_1$ approaches zero.

hep-th↗

arXiv2024

Hydrodynamics of Arcsin AdS Black Brane

In this paper, we explore a modified black brane within AdS spacetime, characterized by the Lagrangian density $\frac{1}{q} \text{arcsin}(qR)-2\Lambda$. Due to the absence of an analytic solution, we approach the Einstein equations using a perturbative method, extending our analysis to the second order in $q$. Subsequently, we compute the ratio of shear viscosity to entropy density. Our results suggest that the KSS Bound is not saturated in this model.

hep-th↗

arXiv2024

Exponential Modification of AdS Black Hole and Thermodynamic Behavior

In this paper, we present an exponential modification for the action of an AdS black hole in the absence of a matter field. An approximated black hole solution is obtained up to the third order of perturbation coefficient. A thermodynamic investigation in canonical ensemble shows that the behavior of a Van der Waals fluid is not seen in this model. Nevertheless, the study of thermodynamic potentials and other related quantities suggests that the thermodynamic phase transitions of the first and second types can occur in this model. The forms of the phase transitions are more similar to the Hawking-Page phase transitions.

hep-th↗

arXiv2024

Non-Abelian Exponential Yang-Mills AdS Black Brane and Transport Coefficients

In this paper, AdS black brane solution of Einstein-Hilbert gravity with non-abelian exponential guage theory of Yang-Mills type is introduced. DC conductivity and the ratio of shear viscosity to entropy density as two important transport coefficients are calculated by using of Kubo formula in the context of AdS/CFT duality. Our results recover the Yang-Mills model in $q\to \infty$ limit.

hep-th↗

arXiv2024

The Phase Transition of $4D$ Yang-Mills Charged GB AdS Black Hole with Cloud of Strings

In this paper, we present an exact spherically symmetric and Yang-Mills charged AdS black hole solution in the context of $4D$ Einstein-Gauss-Bonnet (EGB) gravity in the presence of a cloud of strings. The regularity of the solution is checked. Thermodynamics of this solution is studied. The critical behavior, the types of phase transitions in canonical ensemble, the Joule-Thomson expansion, the Clapeyron equation and the critical exponents shall be investigated.

hep-th↗

arXiv2024

The Phase Transition of Non-minimal Yang-Mills AdS Black Brane

In this paper, we shall study the phase transition of non-minimal coupling of Einstein-Hilbert gravity and electric field of Yang-Mills type in AdS space-time. We couple the Ricci scalar to the Yang-Mills invariant to obtain a modified theory of gravity. A black brane solution is introduced up to the first order of the term $RF^{(a)}_{μα}F^{(a)μα} $ in this model. Then, the phase transition of this solution will be investigated in canonical ensemble. Our investigation shows that only the second order phase transition behavior is seen in this model. Also, due to the coupling of the Yang-Mills field and Ricci scalar, there are differences with the phase transitions of the usual minimal models. We shall show that in the absence of non-minimal coupling there is no any phase transition.

hep-th↗