A. Rohim | Searcharxiv

arXiv2026

Non-extensive entropy signatures in compact star

The non-extensive entropy models applied to the black-hole horizon are connected to the generalized Einstein--Hilbert action, $f(R)$, via the Wald entropy formalism. We demonstrate that quark star configurations characterized by the MIT bag model under this modified gravity approach conform to the observational lower and upper bounds established for compact objects linked to HESS J1731$-$347 and GW190814. Furthermore, we assess the effective energy conditions and corresponding speed of sound to evaluate the physical plausibility and stability of the stellar configurations. All non-extensive entropy models studied satisfied these conditions. Our findings show that the exotic compact objects offer a compelling and credible framework for exploring aspects of non-extensive entropy models, such as the Barrow, Tsallis-Cirto, and R\'enyi formalisms, and vice versa.

gr-qc↗

arXiv2026

A Quantum-Gravity-Motivated GUP Effective Metric

Recent critiques have addressed certain aspects of the generalized uncertainty principle (GUP) effective metric (Ong 2023). This study presents a scale-dependent quadratic GUP effective metric, constructed through analyses of the gravity-induced phase shift (COW experiment) and the Einstein-Bohr photon box Gedanken experiment. In contrast to the procedure outlined in (Xiang et al. 2018), the momentum-dependent metric is improved by introducing an interpolating function $\Delta p (r)$, which employs the effective distance concept to accurately capture the distinct behavior of $\Delta p (r)$ in both short and long distance regimes. The resulting effective metric exhibits the same structure as that derived from the Renormalization Group (RG) theory. However, the RG parameter $\hat{\gamma}$ can now be related to the dimensionless GUP parameter $\beta_0$, thereby distinguishing this metric from the RG-based approach. The corresponding effective metric prediction demonstrates internal consistency of the model, and phenomenologically the predictions are in agreement with some quantum black hole models in some limits. The effective metric improved black hole thermodynamics and shadow predictions compared to the heuristic approach and other proposed GUP effective metrics. Furthermore, the relationship between GUP and $f(R)$ gravity (D'Agostino et al. 2026) may provide a possible future route toward a more fundamental description of GUP.

gr-qc↗