arXiv subjects

Md Khalid Hossain

Publications and source records attributed to Md Khalid Hossain.

7 recordsLinked to original sources

arXiv2026

Charged galactic wormholes: shadow imaging, accretion disks, and charged-particle deflection

We investigate the gravitational deflection of charged massive particles by a charged galactic wormhole supported by the Sofue dark matter density profile \cite{r57}, $ρ(r)=ρ_0 e^{-r/r_0},$ where $ρ_0$ and $r_0$ denote the central dark matter density and the characteristic scale radius, respectively. This phenomenological profile models the dark matter distribution in galactic halos and acts as the matter source sustaining the wormhole geometry. Extending our previous investigation of light rays and neutral massive particles in this spacetime \cite{b1}, we study the combined effects of gravitational and electromagnetic interactions on the motion of charged massive particles. The deflection angle is computed independently using the Rindler--Ishak method based on the Jacobi metric and the Gauss--Bonnet theorem, enabling a systematic comparison between the two approaches. We find that the predictions of the two methods become nearly indistinguishable in the relativistic regime, whereas the differences at lower velocities arise from the velocity-dependent correction terms proportional to $(1-v^2)$ in the trajectory equation. We further perform backward relativistic ray tracing of optically thin accretion flows around the charged galactic wormhole to investigate its shadow and photon-ring structure. Although the shadow remains circular because of the spacetime's spherical symmetry, its radius, photon-ring structure, and intensity distribution exhibit a nontrivial dependence on the wormhole charge, providing potential observational signatures of charged galactic wormholes. These results provide new insights into the interplay between gravitational and electromagnetic interactions in charged wormhole spacetimes and their observational manifestations.

physics.gen-ph↗

arXiv2026

Holographic timelike complexity for de Sitter

We investigate the recent proposal of holographic volume complexity for timelike subregions \cite{Alishahiha:2025xml} in the framework of static patch holography for de Sitter spacetime. Using the stretched-horizon prescription, we compute the timelike subregion complexity as a function of the subregion duration for pure de Sitter and Schwarzschild de Sitter geometries. In pure de Sitter spacetime, the timelike subregion complexity displays exponential growth for short durations, and hyperfast growth near a maximal duration, paralleling the features of spacelike volume complexity \cite{Jorstad:2022mls}. For Schwarzschild de Sitter, when the stretched horizon is near the cosmological horizon, the behavior broadly remains similar to pure de Sitter. However, when the stretched horizon is near the black hole horizon, the hyperfast growth for long durations is replaced by nonlinear growth regime. Along the way, we also compute the corresponding timelike holographic entanglement entropy for de Sitter and Schwarzschild de Sitter.

hep-th↗

arXiv2026

LePREC: Reasoning as Classification over Structured Factors for Assessing Relevance of Legal Issues

More than half of the global population struggles to meet their civil justice needs due to limited legal resources. While Large Language Models (LLMs) have demonstrated impressive reasoning capabilities, significant challenges remain even at the foundational step of legal issue identification. To investigate LLMs' capabilities in this task, we constructed a dataset from 769 real-world Malaysian Contract Act court cases, using GPT-4o to extract facts and generate candidate legal issues, annotated by senior legal experts, which reveals a critical limitation: while LLMs generate diverse issue candidates, their precision remains inadequate (GPT-4o achieves only 62%). To address this gap, we propose LePREC (Legal Professional-inspired Reasoning Elicitation and Classification), a neuro-symbolic framework combining neural generation with structured statistical reasoning. LePREC consists of: (1) a neuro component leverages LLMs to transform legal descriptions into question-answer pairs representing diverse analytical factors, and (2) a symbolic component applies sparse linear models over these discrete features, learning explicit algebraic weights that identify the most informative reasoning factors. Unlike end-to-end neural approaches, LePREC achieves interpretability through transparent feature weighting while maintaining data efficiency through correlation-based statistical classification. Experiments show a 30-40% improvement over advanced LLM baselines, including GPT-4o and Claude, confirming that correlation-based factor-issue analysis offers a more data-efficient solution for relevance decisions.

cs.CL↗

arXiv2026

Revisiting The Gravitational Mirroring In Presence of Compact Objects

We propose a novel concept of astrophysical mirroring in the schwarzschild framework, which emerges as a direct consequence of gravitational lensing effects occurring in the immediate vicinity of extremely dense massive objects within spacetime. Through rigorous theoretical calculations and numerical ray-tracing analysis, we demonstrate that sufficiently compact astrophysical objects possess the capability to induce such extreme curvature in spacetime that the resulting gravitational field can bend light rays to extraordinary degrees, creating what we term a "reflection image" or mirror-like appearance of the source in distant regions of space. We discuss the theoretical framework as well as the observational consequences of this phenomenon.

gr-qc↗

arXiv2025

Catenoid Inspired Hyperbolic Wormhole Geometry

We unveil a novel class of traversable wormholes exhibiting exact spherical symmetry, geometrically inspired by the minimal surface structure of a catenoid. Introducing the spacetime metric, we rigorously derive its fundamental curvature properties, including the Riemann curvature tensor, and consequently compute the Einstein tensor and stress-energy tensor. This framework reveals that the wormhole is sustained by an anisotropic fluid. A detailed analysis of the energy conditions demonstrates the requisite presence of exotic matter, establishing the physical viability and constraints of this configuration. Subsequent investigations address the wormhole's traversability characteristics, gravitational lensing signatures, and dynamic stability. Crucially, we establish that this catenoid-inspired spacetime represents a finite wormhole, possessing bounded spatial extent.

gr-qc↗

arXiv2025

Gravitational Wave Signatures of Periodic Motion near Higher-Derivative Einstein-Æther Black Holes

Higher-derivative modifications of general relativity are generically expected from effective field theory approaches to quantum gravity, and they arise naturally in Lorentz-violating theories such as Einstein-Ether gravity. In this work, we investigate black hole spacetimes within Einstein-Ether theory supplemented by quadratic curvature corrections, including terms proportional to $R^2$, $R_{μν} R^{μν}$, and $R_{μνλρ} R^{μνλρ}$. We derive the corrected static, spherically symmetric metric perturbatively and examine its effects on the geodesic structure and gravitational wave emission. In particular, we analyze periodic timelike orbits in this background and compute the associated tensor-mode gravitational waveforms using the quadrupole approximation. Our results demonstrate that even small higher-derivative corrections can induce distinguishable shifts in the orbital dynamics and imprint characteristic phase modulations and harmonic deformations in the gravitational wave signal. These effects modify the frequency spectrum and amplitude envelope of $h_{+}$ and $h_{\times}$ in a manner sensitive to the coupling constants $α$, $β$, and $γ$, and the Ether parameter $c_{13}$. The resulting signatures provide a potential observational window into ultraviolet deviations from general relativity and Lorentz symmetry in the strong-field regime.

gr-qc↗

arXiv2025

Gravitational lensing due to charged galactic wormhole

We propose the back reaction to the charged galactic wormhole spacetime based on Yoshiaki Sofue's exponential dark matter density profile to find exact solutions. The charges act as an additional component to the static wormhole, which is primarily formed by the galactic dark matter density. Unlike traditional mass-based models, this solution incorporates charge effects within a realistic dark matter distribution, revealing unique interactions between dark matter, electromagnetic fields, and spacetime curvature. This study confirms the criteria for wormhole formation, designating it the "Charged Galactic Wormhole," and offers a new framework for investigating galactic structures, with potential observational signatures that deepen our understanding of dark matter and spacetime. Later, the proper radial distance and the embedding surface were also analyzed. Furthermore, the deflection of light around a charged galactic wormhole was investigated, along with a comprehensive review of the resulting image. The deflection of massive objects (charge less) near charged galactic wormholes is studied using the Gauss-Bonnet and Rindler-Ishak methods, with a detailed comparison of the results from both approaches. Additionally, in both the Rindler-Ishak (RI) and Gauss-Bonnet (GB) methods, when v tends to 1 i.e. when particle's velocity comparable to the speed of light , the results from these approaches converge, producing the same outcome as strong gravitational lensing.

physics.gen-ph↗