arXiv subjects

Amine Bouali

Publications and source records attributed to Amine Bouali.

At least 19 recordsLinked to original sources

arXiv2026

Black Holes Thermodynamic Topology in Sharma-Mittal Statistics

In this study, we explore the thermodynamic topology of black holes within the Sharma-Mittal entropy framework. Our study covers several black hole solutions, including charged and uncharged black holes in $d$-dimensional, as well as Schwarzschild and Reissner-Nordström black holes. By introducing the Sharma-Mittal entropy characterized by two parameters $δ$ and $R$, we explore how deviations from the standard Boltzmann-Gibbs statistics modify the thermodynamic structure and stability properties of these systems. Using Duan's $Φ$-mapping theory, we compute the corresponding topological numbers and classify black holes into distinct topological categories according to the winding number $W$. Moreover, our analysis shows that, within the Sharma-Mittal formalism, the topological classification is independent of spacetime dimension in the case $d>4$, although dimensions higher than four exhibit distinct features compared to the four-dimensional Schwarzschild and Reissner-Nordström black holes, reveal different behavior of thermodynamic topology under generalized statistics.

gr-qc↗

arXiv2026

Testing the running vacuum model in light of DESI-DR2 Measurements

Motivated by the fact that quantum effects leave an imprint on the vacuum equation of state, making it depart from the standard cosmological constant relation, $P_{\rm vac}=-ρ_{\rm vac}$, this work investigates generalized running vacuum models (RVMs) by considering a dynamical vacuum equation of state in which the vacuum energy density, $ρ_{\text{vac}}$, evolves as a function of the Hubble parameter, $H$, and its time derivative, $\dot{H}$. This formulation extends previous running vacuum approaches by incorporating a dependence of the vacuum energy density on both, $H^2$ and $\dot{H}$. The corresponding Friedmann equations are derived and analyzed to study their impact on cosmic expansion. The model parameters are constrained through a joint statistical analysis combining the cosmic microwave background shift parameters, DESI-DR2 observations, PantheonPlus type Ia supernovae compilation, and Hubble rate $H(z)$ measurements. Model comparison is performed using information criteria, the Akaike Information Criterion (AIC) and Deviance Information Criterion (DIC), in order to assess the statistical performance of the RVMs relative to the standard $Λ$CDM scenario. The results show that the generalized RVMs provide a good fit to current observations and represent a statistically competitive alternative to the standard $Λ$CDM model. Notably, all three running vacuum formulations yield lower AIC and DIC values than $Λ$CDM, indicating that dynamical running vacuum energy remains a viable cosmological scenario.

physics.gen-ph↗

arXiv2026

Cosmological Tests of $f(R,G,T)$ Dark Energy Model in FRW Universe

This research article presents a new cosmological model formulated within the $f(R,G,T)$ framework, focusing on the observational signatures and parameter constraints of the model. The Markov Chain Monte Carlo (MCMC) technique is employed to effectively explore the parameter space using data from 36 Cosmic Chronometers and 1701 Pantheon Plus data points. A comparative analysis is conducted between the proposed $f(R,G,T)$ model and the widely accepted $Λ$CDM model, considering various cosmological parameters, such as Deceleration, Snap, and Jerk. By evaluating these parameters, valuable insights into the dynamics and evolution of the universe within the context of the new model are obtained. Diagnostic tests including Statefinder and Om Diagnostic are performed to further investigate the behavior and consistency of the $f(R,G,T)$ model. These tests provide deeper insights into the properties of the model and its compatibility with observational data. The model is subjected to statistical analysis using Information Criteria to rigorously assess its goodness of fit to the data. This analysis helps determine the level of agreement between the $f(R,G,T)$ model and the observational data, establishing the viability and reliability of the proposed cosmological framework. The results highlight the potential of the $f(R,G,T)$ framework in understanding the fundamental aspects of the universe's evolution and dynamics. The comparative analysis with the $Λ$CDM model, along with the comprehensive diagnostic tests performed, demonstrates the efficacy and validity of the $f(R,G,T)$ model in explaining observed cosmological phenomena. These findings contribute to the ongoing pursuit of accurate and comprehensive models that provide a deeper understanding of the nature of our universe.

gr-qc↗

arXiv2026

Cosmological test of a length-preserving biconnection gravity

We investigate the cosmological implications of an extended gravitational framework based on biconnection gravity, constructed from the Schr$\ddot{o}$dinger connection and its dual. In this approach, the difference between the two connections defines the mutual curvature, which encodes the non-Riemannian geometric degrees of freedom, while their symmetric combination reduces to the Levi-Civita connection and hence reproduces general relativity at the background level. Within this setting, we derive the generalized Friedmann equations for a spatially flat Friedmann-Lemaître-Robertson-Walker Universe. The resulting equations contain additional geometric contributions that may naturally encode an effective dark energy sector induced by the biconnection degrees of freedom. We explore this extra dark energy by adopting five commonly used parametrizations, namely B$Λ$CDM, $ω$CDM, Chevallier-Polarski-Linder, Barboza-Alcaniz, and a logarithmic equations of state. These considerations are confronted with recent observational data, including DESI DR2, Pantheon$^+$, and CC observations. Our analysis shows that the four parameterizations enter the acceleration phase at almost the same redshifts and share the same current value of the Hubble rate. Furthermore, the statistical comparison based on the Akaike, Bayesian, and Deviance Information Criterion shows that Barboza-Alcaniz, and logarithmic parameterizations have strong evidence and are competitive with $Λ$CDM. To classify this biconnection gravity in the plethora theoretical models describing the current cosmic acceleration, we examine its implications through cosmographic tools, including the deceleration, jerk, and snap parameters, as well as through the Statefinder analysis and $Om(z)$ diagnostic.

astro-ph.CO↗

arXiv2026

Reconstruction of the Quintessence Scalar Field Potential Using Gaussian Processes

Recent cosmological observations, including the latest Dark Energy Spectroscopic Instrument (DESI) data releases DR1 and DR2, have renewed interest in the possibility that dark energy may exhibit dynamical behavior rather than being a strict cosmological constant. In this work, we perform a fully model-independent reconstruction of the quintessence scalar field potential using Gaussian Process regression and current Hubble measurements. Instead of assuming a specific functional form for the scalar field potential, we reconstruct the quintessence potential and the corresponding kinetic energy directly from observational data. Our analysis is based on Hubble parameter measurements obtained from cosmic chronometers and the latest high-precision DESI DR2 baryon acoustic oscillation (BAO) data, together with Type Ia supernova data from the Pantheon+ compilation. Gaussian Processes provide a nonparametric and model-independent framework that allows the data to guide the reconstruction. We employ two covariance functions, namely the squared exponential and the Matern ($ν= 9/2$) kernels, in order to assess the sensitivity of the reconstruction to the kernel choice. We further explore the impact of background cosmological assumptions by considering different priors on the matter density and spatial curvature. Finally, we compare the reconstructed scalar field potential with two theoretically motivated benchmark models: a power law potential and an exponential potential. We find that both models remain consistent with the reconstructed potential within the inferred confidence intervals.

astro-ph.CO↗

arXiv2026

Study of the cosmological tensions and DESI-DR2 in the framework of the Little Rip model

We present an analysis that investigates the $H_0$ and $S_8$ tensions by considering a dark energy model. The latter is a late-time model characterized by a future abrupt event known as the Little Rip (LR) model and characterised by one extra parameter, $β$, compared to the standard model, $Λ$CDM. To test this approach, we perform a statistical analysis by the MCMC method using the most recent observational data. We obtain a positive correlation in ($H_0$, $β$) plane. We also note that the Hubble tension is less than $3σ$ when using early measurements, i.e., Cosmic Microwave Background (CMB) data, and when combining it with Baryon Acoustic Oscillation (BAO) data, but it is no longer so when we combine early and late measurements (i.e. PantheonPlus (PP)). In addition, we test the model with DESI-DR2 combined with CMB and recent SNIa measurements. We notice that our model shifts toward the quintessence field. For a complete statistical analysis, we use the Akaike Information Criteria and Bayesian analysis of the evidence. According to Bayes factors, we find that the LR model provides an improved fit only to CMB data.

astro-ph.CO↗

arXiv2025

Thermodynamic Topology of Black Holes within Tsallis Statistics

In this paper, we investigate the thermodynamic topology of black holes within the framework of Tsallis statistics. By integrating Tsallis non-extensive statistics with topological thermodynamics, we analyze the local and global stability of various black hole solutions, including Schwarzschild, Reissner-Nordstrom, and higher-dimensional black holes. The introduction of Tsallis entropy, parameterized by the non-extensive parameter delta, results in distinct thermodynamic behaviors depending on its value. Employing Duan's phi-mapping theory, we classify the thermodynamic topology of four-dimensional Schwarzschild black holes and non-charged higher-dimensional black holes into three distinct classes based on their topological number W: stable (W = +1), unstable (W = -1), and critical (W = 0). Additionally, the thermodynamic topology of Reissner-Nordstrom and charged higher-dimensional black holes is categorized into two classes, where W = +1 indicates a stable class and W = 0 represents a less stable class. Our study further demonstrates that the number of dimensions does not affect the topological thermodynamics within the context of non-extensive statistics. This approach provides novel insights into the interplay between Tsallis statistics and black hole thermodynamics, underscoring the pivotal role of topology in understanding black hole physics.

gr-qc↗

arXiv2025

Spacetime Foam Effects on Charged AdS Black Hole Thermodynamics

In this paper, we investigate the emergent thermodynamic phenomena arising from spacetime foam and its impact on black hole behavior. Within this framework, we adopt the Barrow model, where the structure of spacetime at small scales is modeled by analogy with the Koch snowflake, implying that black hole surfaces acquire a quasi-fractal structure due to quantum deformations induced by quantum gravity effects. Our analysis, conducted within the extended phase-space formalism, reveals that the quasi-fractal correction to black hole entropy significantly modifies the equation of state, critical parameters, and phase-transition behavior of charged AdS black holes. An increase in the Barrow parameter leads to higher critical pressure and temperature, which diverge at maximal deformation. Moreover, while the quasi-fractal structure has a negligible effect on small black holes with low entropy, it clearly influences the thermal evolution of medium and large event horizon black holes. Additionally, we study the impact of quasi-fractal corrections on the Joule-Thomson expansion and the phase transition between cooling and heating regimes. We also examine the effects of spacetime structure on black hole microstate density, lifetimes, and temperature detection by different observers, including local, asymptotic, and Unruh detectors. We find that spacetime foam increases microstate density and prolongs evaporation lifetimes, thus acting as a resistance to black hole evaporation, while local observers experience that the expected Tolman blueshift and Unruh temperatures remain unmodified.

hep-th↗

arXiv2025

From Barthel Randers Kropina Geometries to the Accelerating Universe: A Brief Review of Recent Advances in Finslerian Cosmology

We review recent developments in cosmological models based on Finsler geometry and extensions of general relativity within this framework. Finsler geometry generalizes Riemannian geometry by allowing the metric tensor to depend on position and an additional internal degree of freedom, typically represented by a vector field at each point of the spacetime manifold. We explore whether Finsler-type geometries can describe gravitational interaction and cosmological dynamics. In particular, we examine the Barthel connection and $(α, β)$ geometries, where $α$ is a Riemannian metric and $β$ is a one-form. For a specific construction of $β$, the Barthel connection coincides with the Levi-Civita connection of the associated Riemann metric. We review gravitational field and cosmological evolution in three geometries: Barthel-Randers ($F = α+ β$), Barthel-Kropina ($F = α^2 β$), and the conformally transformed Barthel-Kropina geometry. After presenting the mathematical foundations of Finslerian-type modified gravity theories, we derive generalized Friedmann equations in these geometries assuming a Friedmann-Lemaître-Robertson-Walker type metric. We also present the matter-energy balance equations, interpreting them from the perspective of thermodynamics with particle creation. The cosmological properties of Barthel-Randers and Barthel-Kropina models are explored in detail. The additional geometric terms in these models can be interpreted as an effective dark energy component, generating an effective cosmological constant. Several cosmological solutions are compared with observational data (Cosmic Chronometers, Type Ia Supernovae, Baryon Acoustic Oscillations) using MCMC analysis. A comparison with the $Λ$CDM model shows that Finslerian models fit observational data well, suggesting they offer a viable alternative to general relativity.

gr-qc↗

arXiv2025

Model-Independent Reconstruction of f(T) Gravity Using Genetic Algorithms

In this paper, we use genetic algorithms, a specific machine learning technique, to achieve a model-independent reconstruction of $f(T)$ gravity. By using $H(z)$ data derived from cosmic chronometers and radial Baryon Acoustic Oscillation method, including the latest Dark Energy Spectroscopic Instrument (DESI) data, we reconstruct the Hubble rate which is the basis parameter for reconstructing $f(T)$ gravity without any assumptions. In this reconstruction process, we use the current value of the Hubble rate, $H_0$, derived by genetic algorithms. The reconstructed $f(T)$ function is consistent with the standard $Λ$CDM cosmology within the 1$σ$ confidence level across a broad temporal range. The mean $f(T)$ curve, adopting a quadratic form, prompts us to parametrize it using a second degree polynomial. This quadratic deviation from the $Λ$CDM scenario is mildly favored by the data.

astro-ph.CO↗

arXiv2025

Emergence of running vacuum energy in $f(R,T)$ gravity : Observational constraints

In this work, we present a new analysis for $f(R,T)$ gravity by exploring the energy momentum tensor. We demonstrate that $f(R,T)$ gravity with the form $f(R,T)=R+2 κ^2 λT-2Λ$ is equivalent to Running Vacuum Energy (RVE), which interacts with the components of the cosmic fluid, namely dark matter and radiation. Interestingly, the form of such interaction is inferred from the non-conservation of the stress energy tensor in $f(R, T)$ gravity rather than being introduced in a phenomenological manner. Furthermore, the parameters that distinguish RVE from $Λ$CDM are fixed once the parameter of $f(R,T)$ gravity, $λ$, is known. To illustrate our setup, we perform a Markov Chain Monte Carlo analysis of three interaction scenarios using a combination of different data. we find that the parameters characterizing the RVE model are very small as expected. These results give an accuracy to this equivalence between $f(R,T)$ gravity under consideration and support the recent result obtained from a quantum field theory in curved space-time point of view which could open a new relationship between $f(R,T)$ gravity and quantum field theory. Finally, the interaction of the running vacuum increases the value of the current value of the Hubble rate by $3.5\%$ compared to the $Λ$CDM model, which may be a promising study for the Hubble tension.

gr-qc↗

arXiv2024

Extracting $H_{0}$ and $r_{d}$ in Pacif Parametrization Models through Late-Time Dataset

This study examines five models derived from the Pacif parametrization scheme of the Hubble parameter ($H$), yielding various linear to quintic forms of the deceleration parameter (DP). Our goal is to explore the impact of these DP variations on late-time evolution and their potential to alleviate cosmological tensions. To enhance model constraints, we introduce non-diagonal elements into the covariance matrix to better capture statistical properties by simulating data point correlations. We also test the sensitivity of $H_{0}$ and $r_{d}$ to the Pacif parametrization scheme, treating the sound horizon $r_{d}$ as a free parameter to avoid imposing a CMB prior. This allows late-time data to constrain $r_{d}$ alongside other cosmological parameters, incorporating recent Baryon Acoustic Oscillations (BAO) measurements and Hubble data from Cosmic Chronometers Methods, Type Ia Supernovae (SNIa), Gamma-Ray Bursts (GRBs), and Quasars over a redshift range of $0.106 < z < 2.33$. Our analysis provides optimal fit values for $H_{0}$ and $r_{d}$, showing notable consistency with Planck CMB data. By using the Akaike information criterion, we analyze the models and conclude that all models have good agreement with the most recent observations.

astro-ph.CO↗

arXiv2024

Statistical and Observation Comparison of Weyl-Type $f(Q,T)$ Models with the $Λ$CDM Paradigm

We study the $f(Q,T)$ gravity in the framework of Weyl geometry (known as Weyl-type $f(Q,T)$ gravity), where $Q$ denotes the non-metricity scalar, and $T$ denotes the energy-momentum tensor trace. In this work, we consider the $f(Q,T)$ model, which is defined as $f(Q,T)=αQ^{m+1}+\fracβ{6κ^2}T$ and investigating two scenarios: $(I)$ $m=0$ (linear model) and $(II)$ $m\neq 0$ (nonlinear model). For both scenarios, we find the explicit solution for the field equations by using the barotropic equation of state as $p=wρ$, where $w$ is the equation-of-state (EoS) parameter. Further, we study the obtained solutions statistically using the $Pantheon^+$ (Without SHOES Calibrated) dataset with 1701 data points. For both models, the best-fit values of model parameters for $1-σ$ and $2-σ$ confidence level. The higher Hubble constant values in both models emphasize the presence of Tension. We statistically compare our models to the $Λ$CDM model using ${{\protectχ}^2_{min}}$, ${{\protectχ}^2_{red}}$, $AIC$, $ΔAIC$, $BIC$ and $ΔBIC$. We also examine cosmological parameters such as deceleration and EoS parameters to determine the current acceleration expansion of the Universe. Furthermore, we test our model using $Om$ diagnostic and compare it to the $Λ$CDM model to determine its dark energy profile. Finally, we draw the conclusion that statistically speaking, both linear and nonlinear models show good compatibility with the $Λ$CDM model.

gr-qc↗

arXiv2024

Holographic Thermodynamics of BTZ Black Holes and Tsallis Entropy

This paper presents a detailed study of the thermodynamics of charged BTZ black holes using the conformal holographic extended thermodynamics formalism and Tsallis statistics. The cornerstone of our thermodynamic framework is the re-scaling of CFT by the conformal factor, which is considered a thermodynamic parameter. Here, the AdS radius is distinct from the CFT radius, allowing for independent variations of the central charge and volume. Our analysis revealed that the thermodynamic behavior of charged BTZ black holes in three dimensions is characterized by the stability and absence of phase transitions, contrasting with the behavior of four-dimensional black holes. The central charge of CFT notably influences the thermal evolution of these black holes, with a smaller central charge leading to faster thermal processes. Additionally, the temperature of large black holes is proportional to their entropy. By incorporating Tsallis statistics into our study, we found that the stability of black holes depends on the Tsallis parameter. Black holes are always stable when the Tsallis parameter is less than 2. However, if this parameter is greater than 2, a first-order phase transition occurs between small stable and large unstable. Overall, our findings contribute to a deeper understanding of the holographic thermodynamics of lower-dimensional black holes and the impact of non-extensive statistics on their physical properties.

hep-th↗

arXiv2024

Constraints on Power Law and Exponential models in $f(Q)$ Gravity

In this paper, we observationally test the $ f(Q) $ gravity model at both background and perturbation levels using Pantheon$^+$, Hubble measurements, and Redshift Space Distortion Data. We obtain the best-fit parameters by solving numerically the modified Friedmann equations for two distinct cosmological models of $ f(Q) $ gravity namely the Power law and Exponential models. This involves performing a Markov Chain Monte Carlo analysis for these specific forms of $ f(Q) $. To evaluate the statistical significance of the $ f(Q) $ gravity models, we use the Bayesian and corrected Akaike Information Criteria. Our results indicate that the Exponential model in $ f(Q) $ gravity is statistically favored over both the Power-law model and the $ Λ$CDM model.

gr-qc↗

arXiv2024

Observational constraints on the growth index parameters in $f(Q)$ gravity

In this study, we analyse constraints on the growth index of matter perturbations, $γ$, within the framework of $f(Q)$ gravity, using recent cosmological observations, at the background and the perturbation levels, including Pantheon$^{+}$, Cosmic Chronometer (CC), and Redshift Space Distortion (RSD) datasets. Our analysis focuses on quantifying the distortion parameter, which measures the deviation of the $f(Q)$ gravity model from the concordance $Λ$CDM cosmology at the background level. Specifically, we investigate two cases of the growth index parameter: a constant $γ$ and a time-varying $γ(z)$. We investigate various parametrizations of the growth index $γ$, expressed as $γ= γ_{0} +γ_{1} y(z)$, where the function $y(z)$ assumes different forms, including constant ($Γ_{0}$), Taylor expansion around $z = 0$ ($Γ_{1}$), Taylor expansion around the scale factor ($Γ_{2}$), and an exponential form ($Γ_{3}$). By employing the Akaike Information Criterion and Bayesian Information Criterion, we find that the combined Pantheon$^{+}$+ CC+ RSD datasets impose stringent constraints on the value of the growth index. For the $Γ_{0}$ model, our results indicate that within the concordance $Λ$CDM model, $γ$ is constrained to $0.545 \pm 0.096$, showing strong agreement with the theoretical expectation of $γ_Λ = \frac{6}{11}$. However, within the framework of $f(Q)$ gravity, we observe $γ= 0.571^{+0.095}_{-0.110}$, slightly exceeding the $Λ$CDM value by 4.66 $\%$. Furthermore, when considering a time-varying growth index, our analysis reveals that the range of $γ_{0}$ spans from $0.596$ to $0.62$ across the $Γ_{1-3}$ models.

gr-qc↗

arXiv2024

Constraining dark energy equations of state in $F(R,T)$ gravity

In this paper, we examine the acceleration of the Universe's expansion in $F(R,T)$ gravity, where $R$ denotes the Ricci scalar and $T$ the trace of energy-momentum tensor. Indeed, the unknown nature of the source controlling this acceleration in general relativity leads scientists to investigate its properties by means of some alternative theories to general relativity. Our study is restricted to the particular case where $F(R,T)=R+2κ^2 λT$ , with $λ$ being a constant. We use a Bayesian analysis of current observational datasets, including the type Ia supernovae constitution compilation and $H(z)$ measurements, to constrain free parameters of the model. To parametrize dark energy, we consider two well known equations of state. We find the best fit values for each model by running a Markov chain Monte Carlo technic. The best fit parameters are used to compare both models to $Λ$CDM by means of the Akaike information criterion and the Bayesian information criterion. We show that the Universe underwent recently a transition from a deceleration to an acceleration for both models. Furthermore, the data shows a phantom nature of the equation of state for both models.

gr-qc↗

arXiv2024

Barrow Entropy and AdS Black Holes in RPS Thermodynamics

In this paper, we examine the restricted phase space (RPS) thermodynamics for charged AdS black holes by considering the impact of quantum gravity on the event horizon area. The primary aim of this work is to elucidate the influence of quantum gravitational effects on thermodynamic behaviors, critical phenomena, phase transitions, and the stability of black holes. We observe that charged AdS black holes exhibit thermodynamic behavior similar to that of Van der Waals fluids when influenced by quantum gravity. Furthermore, we introduce a novel black hole thermodynamic phenomenon, which we term ``resistance of phase transitions". Our study uncovers a violation of the homogeneity property of the Smarr relation in RPS thermodynamics due to the effects of quantum gravity.

hep-th↗