arXiv subjects

Mirmani Mirjalali

Publications and source records attributed to Mirmani Mirjalali.

5 recordsLinked to original sources

arXiv2026

Nonlinear response of the chiral magnetic effect in the D3/D7 holographic model

We investigate the nonlinear response of the chiral magnetic current to an external magnetic field in a holographic setup. Using the D3/D7 brane system, where the chiral magnetic effect (CME) can be realized by considering rotating probe D7-branes, corresponding to introducing an axial chemical potential, we analyze the current-magnetic field relation beyond the linear regime. Focusing on the vicinity of the phase boundary between the insulating phase and the CME phase, we find that the chiral magnetic current exhibits a multi-valued dependence on the magnetic field, indicating a highly nonlinear response characteristic of this model. We further study the dynamical stability of the insulating phase near the transition point, and show that the presence of both an axial chemical potential and an external magnetic field cooperatively stabilize the system. Our results clarify the interplay between the axial chemical potential and the magnetic field in determining the phase structure and stability of the system, and reveal new nonlinear aspects of chiral transport in holographic gauge theories.

hep-th↗

arXiv2024

Non-Linear Dynamics and Critical Phenomena in the Holographic Landscape of Weyl Semimetals

This study presents a detailed analysis of critical phenomena in a holographic Weyl semi-metal (WSM) using the $D3/D7$ brane configuration. The research explores the non-linear response of the longitudinal current $ J $ when subjected to an external electric field $ E $ at both zero and finite temperatures. At zero temperature, the study identifies a potential quantum phase transition in the $ J $-$ E $ relationship, driven by background parameters the particle mass, and axial gauge potential. This transition is characterized by a unique reconnection phenomenon resulting from the interplay between WSM-like and conventional nonlinear conducting behaviors, indicating a quantum phase transition. Additionally, at non-zero temperature with dissipation, the system demonstrates first- and second-order phase transitions as the electric field and axial gauge potential are varied. The longitudinal conductivity is used as an order parameter to identify the current-driven phase transition. Numerical analysis reveals critical exponents in this non-equilibrium phase transition that show similarities to mean-field values observed in metallic systems.

hep-th↗

arXiv2023

Heat capacities and thermodynamic geometry in deformed Jackiw-Teitelboim gravity

We study the thermodynamics of charged AdS black holes in deformed Jackiw-Teitelboim (dJT) gravity and their phase structures. In this regard, we will find some critical values for the temperature, entropy and charge of the corresponding black holes. We also compute the heat capacities, expansion coefficient and isothermal compressibility as thermodynamic response functions and study their behaviors at the critical points. It will be shown that these variables satisfy the Ehrenfest's equations in the case of second-order phase transition. We employ different formalisms to investigate thermodynamic geometry, such as Weinhold, Ruppeiner and new thermodynamic geometry, then analyze the singularities of the thermodynamic curvatures in this context. We show that these singularities are also correspond to the divergences of the response functions which indicating the critical points of phase transitions.

hep-th↗

arXiv2022

Planar Black Holes in Holographic Axion Gravity: Islands, Page Times, and Scrambling Times

The present work investigates the entanglement entropies of the Hawking radiations, the Page times, and the scrambling times, for the eternal planar black holes in the holographic axion gravity. The solutions correspond to a new class of charged black holes, because the boundary diffeomorphism is broken due to the graviton mass induced by the axion fields in the bulk. The information theoretical aspects of these black hole solutions is determined upon applying the island rule for the entanglement entropy. Like non-extremal charged black holes, the radiation entropy grows linearly in the no-island configurations, while is saturated at late times by asymptotic values set by the Bekenstein-Hawking entropy in the island configurations, with the boundary being located slightly outside the outer horizon. In particular, for the extremal black planes of holographic axion gravity, we find that: (a) the entanglement entropy of the Hawking radiation is ill-defined at the early times when the island is absent; (b) it tends to a distinctive constant at the late times; (c) the late-time location of the island is indeed universal. Moreover, we investigate how the Page time is affected by the holographic massive gravity deformation. For neutral solutions at the small deformation parameter, and for charged solutions with almost-extremal deformation parameter, we find that the Page transition happens at earlier times.

hep-th↗

arXiv2022

Probing inside a charged hairy black hole in massive gravity

In this paper, we investigate the internal structure of a charged hairy black hole solution in the non-linear massive gravity. We first consider the impact of various configurations of massive gravity on the condensate operator and then probe the black hole interior dynamics. Like a standard holographic superconductor system, just below the critical temperature, the interior evolves through several distinct epochs, including a collapse of the Einstein-Rosen bridge, Josephson oscillations of the scalar field, and finally a Kasner (or Kasner inversion) cosmology. However, for the large massive gravity parameter, we see distinguishing features for the interior dynamics. In this regime, at a given temperature, the Einstein-Rosen bridge collapse and subsequent Josephson oscillations epochs completely disappear from the interior dynamics and the final Kasner cosmology epoch starts exactly after the would-be inner horizon and the system does not experience the Kasner inversion epoch.

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