arXiv subjects

M. Bennai

Publications and source records attributed to M. Bennai.

At least 37 records · Page 2Linked to original sources

arXiv2022

Quintessence Universe and cosmic acceleration in $f(Q,T)$ gravity

The problem of cosmic acceleration and dark energy is one of the mysteries presently posed in the scientific society that general relativity has not been able to solve. In this work, we have considered alternative models to explain this late-time acceleration in a flat Friedmann-Lemaî% tre-Robertson-Walker (FLRW) Universe within the framework of the $% f\left(Q,T\right) $\ modified gravity theory (where $Q$ is the non-metricity and $T$ is the trace of the energy-momentum tensor) recently proposed by Xu et al. (Eur. Phys. J. C 79 (2019) 708), which is an extension of $f\left( Q\right) $ gravity with the addition of the $T$ term. Here, we presume a specific form of $f\left( Q,T\right) =αQ+βQ^{2}+γT$ where $% α$, $β$ and $γ$ are free model parameters, and obtained the exact solutions by assuming the cosmic time-redshift relation as $t(z)=\frac{% nt_{0}}{m}g(z)$ which produces the Hubble parameter of the form $H(z)=\frac{% mH_{0}}{m+n}\left[ \frac{1}{g(z)}+1\right] $ where $m$ and $n$ are the non-negative constants, we find the best values for them using 57 data points of the Hubble parameter $H\left( z\right) $. Also, we find the behavior of different cosmological parameters as the deceleration parameter $% \left( q\right) $, energy density $\left( ρ\right) $, pressure $% \left(p\right) $ and EoS parameter $\left( ω\right) $ and compare them with the observational results. To ensure the validity of the results, we studied the energy conditions along with jerk parameter. Finally, we find that our model behaves similarly to the quintessence Universe.

gr-qc↗

arXiv2022

Barrow holographic dark energy models in $f\left( Q\right)$ symmetric teleparallel gravity with Lambert function distribution

The paper presents Barrow holographic dark energy (infrared cut-off is the Hubble horizon) suggested by Barrow recently (Physics Letters B 808 (2020): 135643) in an anisotropic Bianchi type-I Universe within the framework of $% f\left( Q\right) $ symmetric teleparallel gravity, where the non-metricity scalar $Q$ is responsible for the gravitational interaction. We consider two cases: Interacting and non-interacting models of pressureless dark matter and Barrow holographic dark energy by solving $f\left( Q\right) $ symmetric teleparallel field equations. To find the exact solutions of the field equations, we assume that the time-redshift relation follows a Lambert function distribution as $t\left( z\right) =\frac{mt_{0}}{l}g\left( z\right) $, where $g\left( z\right) =LambertW\left[ \frac{l}{m}e^{\frac{l-\ln \left( 1+z\right) }{m}}\right] $, $m$ and $l$ are non-negative constants and $t_{0}$ represents the age of the Universe. Moreover, we discuss several cosmological parameters such as energy density, equation of state (EoS) and skewness parameters, squared sound speed, and $(ω_{B}-ω_{B}^{^{\prime }})$ plane. Finally, we found the values of the deceleration parameter (DP) for the Lambert function distribution as $q_{(z=0)}=-0.45$ and $q_{(z=-1)}=-1$ which are consistent with recent observational data, i.e. DP evolves with cosmic time from initial deceleration to late-time acceleration.

gr-qc↗

arXiv2022

Accelerating Universe scenario in anisotropic $f\left( Q\right) $ cosmology

In this paper, we investigate the exact solution of an anisotropic space-time in the context of $f(Q)$ gravity, where $f\left( Q\right) $ is the arbitrary function of the non-metricity scalar $Q$. Here, we consider a specific power-law form as $f\left( Q\right) =αQ^{n+1}+β$, where $α$, $β$, and $n$ are free model parameters. Using power-law cosmology ($a\left( t\right) \propto t^{m}$), we analyze the physical behavior of cosmological parameters such as the energy density, pressure, EoS parameter, skewness parameter. Further, we validated the model with energy conditions and found that our $f\left( Q\right) $\ cosmological model behaves like the quintessence model in the present and $% Λ$CDM in the future.

gr-qc↗

arXiv2022

Flat FLRW Universe in logarithmic symmetric teleparallel gravity with observational constraints

In this paper, we investigate the homogeneous and isotropic flat FLRW Universe in the logarithmic form of $f\left( Q\right) $ gravity, where $% Q $ is the non-metricity scalar, specifically, $f\left( Q\right) =α+β\log \left( Q\right) $, where $α$ and $β$ are free model parameters. In this study, we consider a parametrization of the Hubble parameter as $H\left( z\right) =η\left[ (z+1)^{-γ}+1\right] $, where $γ$ and $η$ are model/free parameters which are constrained by an $R^{2}$-test from 57 points of the Hubble datasets in the redshift range $0.07<z<2.36$. Further, we investigate the physical properties of the model. We analyze the energy conditions to check the compatibility of the model. We found the SEC is violated for the logarithmic form of $f\left( Q\right) $ gravity due to the reality that the Universe in an accelerating phase. Finally, we discuss some important cosmological parameters in this context to compare our model with dark energy models such as jerk parameter and statefinder parameters.

gr-qc↗

arXiv2022

Late-time acceleration in $f\left( Q\right) $ gravity: Analysis and constraints in an anisotropic background

This paper is devoted to investigate the anisotropic locally rotationally symmetric (LRS) Bianchi type-I space-time in the context of the recently proposed $f(Q)$ gravity in which $Q$ is the non-metricity scalar. For this purpose, we consider a linear form of $f\left( Q\right) $ gravity model, specifically, $f\left( Q\right) =αQ+β$, where $α$ and $% β$ are free parameters and we analyzed the exact solutions of LRS Bianchi type-I space-time. The modified Friedmann equations are solved by presuming an expansion scalar $θ\left( t\right) $ is proportional to the shear scalar $σ\left( t\right) $ which leads to the relation between the metric potentials as $A=B^{n}$ where $n$ is an arbitrary constant. Then we constrain our model parameters with the observational Hubble datasets of 57 data points. Moreover, we discuss the physical behavior of cosmological parameters such as energy density, pressure, EoS parameter, and deceleration parameter. The behavior of the deceleration parameter predicts a transition from deceleration to accelerated phases in an expanding Universe. Finally, the EoS parameter indicates that the anisotropic fluid behaves like the standard $Λ$CDM model.

gr-qc↗

arXiv2022

Anisotropic nature of space-time in $f(Q)$ gravity

In this paper, we consider the Bianchi type-I space-time with perfect fluid as matter content of the Universe in the framework of $f(Q)$ gravity (where $% Q$ is the non-metricity scalar) recently proposed by Jiménez et al. (Phys. Rev. D 98.4 (2018): 044048). We find exact solutions of the field equations using the anisotropic property of space-time for volumetric hybrid expansion. The cosmological parameters for the linear form of non-metricity scalar i.e. $f\left( Q\right) =αQ+β$ (where $α$ and $β$ are free model parameters) are discussed and compared with recent Hubble measurements. Also, we have obtained the best fitting values of the model parameters $k, n$ and $H_{0}$ by constraining our model with updated Hubble datasets consisting of 57 data points ($31$ (DA) and $26$ (BAO+other)) along with also examined the stability of the model and test its validity by energy conditions.

gr-qc↗

arXiv2022

Stability analysis of anisotropic Bianchi type-I cosmological model in teleparallel gravity

In this work, we study a cosmological model of Bianchi type-I Universe in teleparallel gravity for a perfect fluid. To obtain the cosmological solution of the model, we assume that the deceleration parameter is a linear function of the Hubble parameter $H$ i.e. $q=-1+βH$ (where $β$ as a positive constant). Consequently, we get a model of our Universe, where it goes from the initial phase of deceleration to the current phase of acceleration. We have discussed some physical and geometric properties such as Hubble parameter, deceleration parameter, energy density, pressure, and equation of state (EoS) parameter and study their behavior graphically in terms of redshift and compare it with observational data such as Type Ia supernovae (SNIa). We also discussed the behavior of other parameters such as the Jerk parameter, Statefinder parameters and we tested the validity of the model by studying the stability analysis and energy conditions.

gr-qc↗

arXiv2022

Holographic dark energy in Gauss-Bonnet gravity with Granda-Oliveros cut-off

In this paper, we have studied a model of holographic dark energy (HDE) with a homogeneous and anisotropic Bianchi type-I Universe in the framework of Gauss-Bonnet (GB) gravity or $f(G)$ gravity. To find an exact solution of the field equations, we assume that the deceleration parameter varies with cosmic time $\left( t\right) $. We plot some physical quantities and give interpretations of the results obtained. Finally, we compared our model with the $ΛCDM$ model by analyzing the Jerk parameter, and we examine the equivalence between the HDE of the present work and the generalized HDE.

gr-qc↗

arXiv2022

Cosmic acceleration and energy conditions in $Λ$CDM symmetric teleparallel $f(Q)$ gravity

In this paper, we study a spatially homogeneous and isotropic FLRW cosmological model in framework of the symmetric teleparallel $f(Q)$ gravity proposed by Jimenez et al. (Physical Review D 98.4 (2018): 044048), where the non-metricity $Q$ is responsible for the gravitational interaction. For the whole analysis we have considered a special form of $f\left(Q\right)$ gravity function i.e. $f\left( Q\right) =αQ^{n}+β$ (where $α$, $β$, and $n$ are the dynamical model constant parameters) in the direction of $t\left( z\right) =\frac{kt_{0}}{b}f\left( z\right)$, where, $f\left( z\right) =W\left[ \frac{b}{k}e^{\frac{b-\ln \left(1+z\right) }{k}}\right] $ and $W$ denotes the Lambert function. We have discussed two cases of the function: linear $f(Q)$ model towards $ n=1$ and quadratic for $n=2$. In both the model we had verified the validity of the models with the help of energy conditions along with some physical parameters like equation of state parameter, jerk parameter, statefinder parameters are also discussed in details and compared it with the observational data.

gr-qc↗

arXiv2021

Preheating and Reheating Constraints in Supersymmetric Braneworld Inflation

We study the evolution of the Universe at early stages, we discuss also preheating in the framework of hybrid braneworld inflation by setting conditions on the coupling constants $λ$ and $g$\ for effective production of $χ$-particles. Considering the phase between the time observable CMB scales crossed the horizon and the present time, we write reheating and preheating parameters $N_{re}$, $T_{re}$ and $N_{pre}$ in terms of the scalar spectral index $n_{s}$, and prove that, unlike the reheating case, the preheating duration does not depend on the values of the equation of state $ω^{\ast }$. We apply the slow-roll approximation in the high energy limit to constrain the parameters of D-term hybrid potential. We show also that some inflationary parameters, in particular, the spectral index $n_{s}$ demand that the potential parameter $α$ is bounded as $α\geq 1$ to be consistent with $Planck$'s data, while the ratio $r$ is in agreement with observation for $ α\leq 1 $ considering high inflationary e-folds. We also propose an investigation of the brane tension effect on the reheating temperature. Comparing our results to recent CMB measurements, we study preheating and reheating parameters $N_{re}$, $T_{re}$ and $N_{pre}$ in the Hybrid D-term inflation model in the range $0.8\leq α\leq 1.1$\, and conclude that $T_{re}$ and $N_{re}$ require $α\leq 1$, while for $N_{pre}$ the condition $α\leq 0.9$ must be satisfied, to be compatible with $Planck$'s results.

astro-ph.CO↗

arXiv2021

Charged 4D Einstein-Gauss-Bonnet Black Hole: Vacuum solutions, Cauchy Horizon, Thermodynamics

In this paper, we investigate the four-dimensional Einstein-Gauss-Bonnet black hole. The thermodynamic variables and equations of state of black holes are obtained in terms of a new parameterization. We discuss a formulation of the van der Waals equation by studying the effects of the temperature on P-V isotherms. We show the influence of the Cauchy horizon on the thermodynamic parameters. We prove by different methods, that the black hole entropy obey area law (plus logarithmic term that depends on the Gauss-Bonnet coupling α). We propose a physical meaning for the logarithmic correction to the area law. This work can be extended to the extremal EGB black hole, in that case, we study the relationship between compressibility factor, specific heat and the coupling α.

gr-qc↗

arXiv2021

Particle-antiparticle in 4D charged Einstein-Gauss-Bonnet black hole

We study the charge of the 4D-Einstein-Gauss-Bonnet black hole by a negative charge and a positive charge of a particle-antiparticle pair on the horizons r- and r+, respectively. We show that there are two types of the Schwarzschild black hole. We show also that the Einstein-Gauss-Bonnet black hole charge has quantified values. We obtain the Hawking-Bekenstein formula with two logarithmic corrections, the second correction depends on the cosmological constant and the black hole charge. Finally, we study the thermodynamics of the EGB-AdS black hole.

gr-qc↗

arXiv2020

A new unified model of dark matter and dark energy in 5-dimensional $f(R,ϕ)$ gravity

We propose a new unified model that describes~dark energy and dark matter in the context of $f(R,ϕ)$ gravity using a massive scalar field in five dimensions. The scalar field is considered in the bulk that surrounds the 3-brane in branworld model. We show that for a specific choice of the $% f(R,ϕ)$ function, we can describe the Einstein gravitation in 4-dimensional space-time. We obtain a relationship between the speed of the universe's expansion and the speed of the bulk's expansion. We also propose that the dark matter is represented by the scalar field mass and that the dark energy is a kinetic energy of this field. Finally, we show that, according to conditions, one can obtain the percentages of density\ of dark matter and the density of ordinary matter.

gr-qc↗

arXiv2020

Classical simulation of qubit by a new hardware design and its applications

In this paper, we develop a new classical simulation of quantum bit (qubit) by use of analog components in order to be able to simulate the quantum properties such as the superposition of states. As part of this new approach, we have also implemented many logical gates (Pauli-X, Hadamard, and Conditional phase-shift gates). Simulation of Hadamard and Conditional phase-shift gates using Proteus Design Suite is also presented and discussed in this work.

quant-ph↗

arXiv2018

On Chaplygin Gas Braneworld Inflation with Monomial Potential

In this paper we study the Chaplygin gas model as a candidate for inflation in the framework of the Randall Sundrum type-II braneworld model. We consider the original and generalized Chaplygin gas model in the presence of monomial potential. The inflationary spectrum perturbation parameters are reformulated and evaluated in the high-energy limit and we found that they depend on several parameters. We also showed that these perturbation parameters are widely compatible with the recent Planck data for a particular choice of the parameters space of the model. A suitable observational central value of $n_{s}\simeq $ $0.965$ is also obtained in the case of original and generalized Chaplygin gas.

gr-qc↗

arXiv2011

On Braneworld Inflation Models in Light of WMAP7 data

We are interested on studing various inflationary spectrum perturbation parameters in the context of the Randall-Sandrum type 2 Braneworld model. We consider in particular three types of potentials. We apply the slow-roll approximation in the high energy limit to constraint the parameter potentials by confronting our results to recent WMAP7 observations. We show that, for some values of the e-folding number N; the monomial potential provides the best fit results to observations data.

hep-th↗

arXiv2011

An exact solution to the Extended Hubbard Model in 2D for finite size system

An exact analytical diagonalization is used to solve the two dimensional Extended Hubbard Model for system with finite size. We have considered an Extended Hubbard Model (EHM) including on-site and off-site interactions with interaction energy U and V respectively, for square lattice containing 4*4 sites at one-eighth filling with periodic boundary conditions, recently treated by Kovacs et al [1]. Taking into account the symmetry properties of this square lattice and using a translation linear operator, we have constructed a r-space basis, only, with 85 state-vectors which describe all possible distributions for four electrons in the 4*4 square lattice. The diagonalization of the 85*85 matrix energy allows us to study the local properties of the above system as function of the on-site and off-site interactions energies, where, we have shown that the off-site interaction encourages the existence of the double occupancies at the first exited state and induces supplementary conductivity of the system.

cond-mat.stat-mech↗

arXiv2010

Chaplygin gas braneworld inflation according to WMAP7 data

We consider a Chaplygin gas model with an exponential potential in framework of braneworld inflation. We apply the slow-roll approximation in the high-energy limit to derive various inflationary spectrum perturbation parameters. We show that the inflation observables depend only on the e-folding number N and the final value of the slow-roll parameter e(end). Whereas for small running of the scalar spectral index dns/dlnk, the inflation observables are in good agreement with recent WMAP7 data.

hep-th↗