arXiv subjects

Antonio Pasqua

Publications and source records attributed to Antonio Pasqua.

At least 19 recordsLinked to original sources

arXiv2026

Reconstruction of f(Q,T) Gravity from Logarithmically Corrected Ricci-Gauss-Bonnet Holographic Dark Energy

The current paper reports an investigation on the cosmological and thermodynamic behaviour of an $f(Q,T)$ modified-gravity framework in which the gravitational Lagrangian is written as $f(Q,T)=f(Q)+λT$, with $Q$ denoting the non-metricity scalar and $T$ the trace of the energy-momentum tensor. The modified Friedmann equations are formulated in terms of an effective Dark Energy sector, and the corresponding equation of state and squared speed of sound are examined for a phenomenological polynomial form of $f(Q)$. A power-law background is constrained using 32 Cosmic Chronometer measurements. The resulting background is then used to study the effective Dark Energy dynamics and its classical stability in the redshift range considered. In this study, we further construct a generalized Ricci-Gauss-Bonnet holographic Dark Energy model with logarithmic entropy corrections based on the Nojiri-Odintsov prescription and establish a correspondence between its energy density and the effective Dark Energy density of the $f(Q,T)$ framework. The full function $f(Q,T)$ is then given by adding the trace contribution $λT$. Finally, the thermodynamic behaviour of the reconstructed model is studied at the apparent horizon with the Nojiri-Odintsov entropy motivated by \textit{Phys. Rev. D} \textbf{105}, 044042 (2022) and the Gibbs relation. The entropy evolution obtained from the compact background description is also found to be consistent with that obtained from the reconstructed effective-fluid formulation, with only small numerical residuals. These results provide a consistent framework for examining the connection between generalized holographic dark energy, reconstructed $f(Q,T)$ gravity, and cosmic thermodynamics.

gr-qc↗

arXiv2026

Scalar Field Reconstructions of Standard, Power Law and Logarithmic Holographic Dark Energy with a Gauss-Bonnet IR cut-off

In this paper, we investigate the Holographic Dark Energy (HDE) model and its entropy-corrected versions, namely the Power Law and Logarithmic entropy corrected HDE models, by considering the infrared cut-off $L=\mathcal{G}^{-1/4}$, where $\mathcal{G}$ is the Gauss-Bonnet invariant. We derived the Equation of State parameter $ω_D$, the deceleration parameter $q$ and the evolutionary form of the fractional energy density of DE $Ω_D'$ for flat and non-flat universes, with and without interaction between DE and Dark Matter. We also analyzed the asymptotic behavior in the DE dominated epoch. Furthermore, correspondences between the considered HDE models and several scalar field models, including tachyon, k-essence, quintessence, Generalized Chaplygin Gas, Yang-Mills, and Nonlinear Electrodynamics models, were established.

gr-qc↗

arXiv2025

Generalized Holographic and Ricci Dark Energy: Cosmological Diagnostics and Scalar Field Realizations

In this work, we present two generalized formulations of the Holographic and Ricci Dark Energy (DE) models, given by $ ρ_{GH} = 3c^2M^{2}_{pl} \left[ 1-ε\left(1-\frac{R}{H^2}\right) \right]H^2$ and $ρ_{GR} = 3c^2M^{2}_{pl}\left[ 1-η\left(1-\frac{H^2}{R}\right) \right]R$ where $H$ and $R$ denote the Hubble parameter and the Ricci scalar, while $ε$ and $η$ are model parameters related by $ε= 1 - η$. We derived explicit analytical expressions for key cosmological quantities, including the Hubble parameter, the DE density $ρ_D$, the DE pressure $p_D$, the equation of state parameter of DE $ω_D$ and the deceleration parameter $q$. The analysis was carried out for four distinct cases: (i) the standard model in its original formulation; (ii) the inclusion of spatial curvature; (iii) the addition of interactions between the dark sectors; and (iv) the presence of both interaction and curvature. Moreover, we also considered the limiting case of a DE Dominated Universe. To further characterize the dynamical features of the models, we investigated several diagnostic tools, namely the statefinder parameters, the $Om(z)$ diagnostic, the squared speed of the sound $v_s^2$, the cosmographic parameters and the age of the present Universe. Moreover, we established a correspondence between the DE models we studied and some scalar field theories, including tachyon, k-essence, dilaton, quintessence, Dirac-Born-Infeld, Yang-Mills and Nonlinear Electrodynamics (NLED) fields.

gr-qc↗

arXiv2025

A Higher-Derivative Hubble Parameter Dark Energy Model: Cosmological Analysis and Scalar Field Correspondence

In this work, we study a Dark Energy (DE) energy density model which depends on the Hubble parameter squared $H^2$ and on its first, second and third time derivatives $\dot{H}$, $\ddot{H}$ and $\dddot{H}$. Considering a scale factor $a$ with a power-law dependence on the time (with $n$ indicating the power-law index), we obtain some important cosmological quantities as function of the , like the energy densities of Matter $ρ_m$ and of DE $ρ_D$, the fractional energy densities of DM $Ω_m$ and of DE $Ω_D$, the Hubble parameter squared $H^2$, the deceleration parameter $q$, the evolutionary form of the fractional energy density of DE $Ω'_D$, the pressure of DE $p_D$ and the Equation of State (EoS) parameter of DE $ω_D$, for both non interacting and interacting cases. For the interacting case, we consider 9 different interacting term $Q$, all functions of the Hubble parameter $H$ and/or of $ρ_m$ and $ρ_D$. Finally, we establish a correspondence between the DE model we study and some scalar field theories, including tachyon, k-essence, quintessence, Yang-Mills (YM) and Nonlinear Electrodynamics (NLED) fields.

gr-qc↗

arXiv2025

New HDE models with higher derivatives of the Hubble parameter $H$

In this work, we investigate two Dark Energy (DE) models characterized by higher-order derivatives of the Hubble parameter $H$, which generalize previously proposed DE scenarios. Assuming a power-law form of the scale factor $a(t)$ given by $a(t)=b_0t^n$, we derive analytical expressions for the DE energy density, pressure, the Equation of State (EoS) parameter, the deceleration parameter and the evolutionary form of the fractional DE density. Both non-interacting and interacting dark sector frameworks are examined, with the interaction modeled through a coupling term proportional to the Dark Matter (DM) energy density. For specific parameter sets corresponding to power-law indices $n=2$, $n=3$, and $n=4$, we compute the present age of the Universe. The values obtained slightly deviate from the observationally inferred age of $\approx 13.8$ Gyr; moreover, a systematic trend is identified, with larger $n$ leading to higher ages. Furthermore, interacting scenarios consistently predict larger ages compared to their non-interacting counterparts. These results highlight the phenomenological viability and limitations of higher-derivative DE models in describing the cosmic evolution.

gr-qc↗

arXiv2025

Scalar Field Reconstructions of Holographic Dark Energy Models with Applications to Chaplygin Gas, DBI, Yang-Mills, and NLED Frameworks

In this study, we investigate the cosmological implications of two DE models, introduced by Chen \& Jing \cite{modelhigher} and by Granda \& Oliveros \cite{gohnde}. The first model comprises three principal components: one term proportional to the Hubble parameter $ H$ squared, and two additional terms proportional to the first and second time derivatives of $ H $, respectively. The second model, known as New Holographic Dark Energy (NHDE) model, can be considered a generalization of the Ricci DE model and it contains a term proportional to the Hubble parameter $H$ squared and one to the first time derivative of $H$. We derive the analytical expressions for the reduced Hubble parameter squared $h^2$, the Equation of State (EoS) parameter of Dark Energy (DE) $ω_D $, the pressure of DE $p_D$ and of the deceleration parameter $q $ considering both non-interacting and later on interacting DM and DE. We also consider some limiting cases for the integration constants obtained. Furthermore, we explore the limiting scenario of a flat, dark energy-dominated Universe and establish a correspondence between the proposed DE models and various scalar field frameworks. Specifically, we examine their connection with the Generalized Chaplygin Gas, the Modified Chaplygin Gas, the Modified Variable Chaplygin Gas, the Viscous Generalized Chaplygin Gas, as well as scalar field models based on Dirac-Born-Infeld theory, Yang-Mills theory and Nonlinear Electrodynamics.

gr-qc↗

arXiv2025

Power-Law and Logarithmic Entropy-Corrected Ricci Dark Energy in a Non-Flat FRW Universe with Viscous Interaction

In this work, we consider the power-law corrected and the logarithmic-corrected versions of the Holographic Dark Energy (HDE) model in a non-flat FRW Universe filled with a viscous Dark Energy (DE) interacting with Dark Matter (DM). We propose to replace the infrared cut-off with the inverse of the Ricci scalar curvature $R$. We obtain the equation of state (EoS) parameter $ω_Λ$, the deceleration parameter $q$ and the evolution of energy density parameter $Ω_Λ '$ in the presence of interaction between DE and DM for both corrections. We study the correspondence of the power-law entropy corrected Ricci dark energy (PLECRDE) and the logarithmic entropy corrected Ricci dark energy (LECRDE) models with the Generalized Chaplygin Gas (GCG), the Modified Variable Chaplygin Gas (MVCG), the New Modified Chaplygin Gas (NMCG), the Yang-Mills (YM) and the Non Linear Electro-Dynamics (NLED) scalar field models.

gr-qc↗

arXiv2025

Expansion Evolution of Nonhomogeneous Metric with Quantum-Mechanically Revisited Fundamental Metric Tensor

To explore the properties of space and initial singularities in the context of general relativity, where spacetime becomes poorly defined and no longer belongs to a regular manifold, we examine the evolution of the expansion of timelike geodesic congruences for two distinct formulations of the fundamental metric tensor. This analysis is conducted within a nonhomogeneous, anisotropic, and spherically symmetric cosmic background. The results derived from the conventional metric tensor, the building block of Einstein's theory of general relativity, are compared with those obtained from a quantum-mechanically revisited metric tensor. This comparison enables an assessment of the proposed geometric quantization, particularly in terms of whether singularities are regulated or diminished. Utilizing a quantum geometric approach, the numerical analysis incorporating a quantum-mechanically revisited metric tensor applies a mean-field approximation on the integrated quantum operators. In contrast to the results obtained with conventional metric tensor, the quantum-mechanically induced revision of the metric tensor seems to provide a framework for controlling singularities in the new formulation of general relativity. The degree of quantization likely influences the ability to regulate or even potentially remove both singularities. We also conclude that the proposed geometric quantization provides a means to explore the quantum nature of spacetime curvatures, emphasizing that the singularity dilemma arose primarily from the standard semi-classical approximation of Einstein's general relativity.

gr-qc↗

arXiv2024

Reconstruction schemes of scalar field models for the Power Law Entropy Corrected Holographic Dark Energy model with Ricci scalar cut-off

In this work, we examine the cosmological characteristics of the Power Law Entropy Corrected Holographic Dark Energy (PLECHDE) model with infrared (IR) cut-off, which is determined by the curvature parameter $k$, the time derivative of $H$, and the average radius of the Ricci scalar curvature $R$, which varies with the Hubble parameter $H$ squared. We obtain the deceleration parameter $q$ and the Equation of State (EoS) parameter of Dark Energy (DE) $ω_D$. Additionally, we derive the Hubble parameter $H$ and the scale factor $a$ expressions as functions of the cosmic time $t$. Additionally, we examine the limiting scenario that pertains to a flat Dark Dominated Universe. Furthermore, we establish a correspondence between the DE model considered and some scalar fields, in particular the Generalized Chaplygin Gas, the Modified Chaplygin Gas, the Modified Variable Chaplygin Gas, the New Modified Chaplygin Gas, the Viscous Generalized Chaplygin Gas, the Dirac-Born-Infeld, the Yang-Mills, and the Non Linear Electrodynamics scalar field models.

gr-qc↗

arXiv2022

Einstein-aether scalar-tensor anisotropic constant-roll inflationary scenario in noncommutative phase space

The primary purpose of this study is to investigate the constant-roll inflationary scenario with anisotropic conditions concerning the Einstein-aether Scalar-tensor cosmology in noncommutative phase space. We first introduce an Einstein-aether scalar-tensor cosmological model. In this structure, one can introduce an aether field with aether coefficients in the action integral of scalar-tensor. It will be a function of the scalar field, which is, in fact, a kind of extender of the Lorentz-violating theories. Hence, we present the point-like Lagrangian, which represents the field equations of the Einstein-aether scalar-tensor model. Then we calculate the Hamiltonian of our model directly. According to the noncommutative phase space characteristics, we will calculate the specific equations of this model. Then, according to the constant roll conditions, we take the anisotropic constant-roll inflationary scenario and calculate some cosmological parameters of the mentioned model, such as the Hubble parameter, potential, etc.

gr-qc↗

arXiv2019

A look into the cosmological consequences of a dark energy model with higher derivatives of $H$ in the framework of Chameleon Brans-Dicke Cosmology

In this paper, we study some relevant cosmological features of a Dark Energy (DE) model with Granda-Oliveiros cut-off, which is just a specific case of Nojiri-Odintsov holographic DE unifying phantom inflation with late-time acceleration, in the framework of Chameleon Brans-Dicke (BD) Cosmology. Choosing a particular ansatz for some of the quantities involved, we derive the expressions of some important cosmological quantities, like the Equation of State (EoS) parameter of DE $w_D$, the effective EoS parameter $w_{eff}$, the pressure of DE $p_D$ and the deceleration parameter $q$. Moreover, we study the behavior of statefinder parameters $r$ and $s$, of the cosmographic parameters $j$, $s_{cosmo}$, $l$ and $m$ and of the squared speed of the sound $v_s^2$ for both case corresponding to non interacting and interacting Dark Sectors. We also plot the quantities we have derived and we calculate their values for $t\rightarrow 0$ (i.e. for the beginning of the Universe history), for $t\rightarrow \infty$ (i.e. for far future) and for the present time, indicated with $t_0$. The EoS parameters have been tested against various observational values available in the literature.

gr-qc↗

arXiv2018

Localization of Energy-Momentum for a Black Hole Spacetime Geometry with Constant Topological Euler Density

The evaluation of the energy-momentum distribution for a new four-dimensional, spherically symmetric, static and charged black hole spacetime geometry with constant non-zero topological Euler density is performed by using the energy-momentum complexes of Einstein and Møller. This black hole solution was recently developed in the context of the coupled Einstein--non-linear electrodynamics of the Born-Infeld type. The energy is found to depend on the mass $M$ and the charge $q$ of the black hole, the cosmological constant $Λ$ and the radial coordinate $r$, while in both prescriptions all the momenta vanish. Some limiting and particular cases are analyzed, illustrating the rather extraordinary character of the spacetime geometry considered.

gr-qc↗

arXiv2017

Energy-momentum for a charged nonsingular black hole solution with a nonlinear mass function

The energy-momentum of a new four-dimensional, charged, spherically symmetric and nonsingular black hole solution constructed in the context of general relativity coupled to a theory of nonlinear electrodynamics is investigated, whereby the nonlinear mass function is inspired by the probability density function of the continuous logistic distribution. The energy and momentum distributions are calculated by use of the Einstein, Landau-Lifshitz, Weinberg and Møller energy-momentum complexes. In all these prescriptions it is found that the energy distribution depends on the mass $M$ and the charge $q$ of the black hole, an additional parameter $β$ coming from the gravitational background considered, and on the radial coordinate $r$. Further, the Landau-Lifshitz and Weinberg prescriptions yield the same result for the energy, while in all the aforesaid prescriptions all the momenta vanish. We also focus on the study of the limiting behavior of the energy for different values of the radial coordinate, the parameter $β$, and the charge $q$. Finally, it is pointed out that for $r\rightarrow \infty$ and $q = 0$ all the energy-momentum complexes yield the same expression for the energy distribution as in the case of the Schwarzschild black hole solution.

gr-qc↗

arXiv2016

Cosmological reconstruction and {\it Om} diagnostic analysis of Einstein-Aether Theory

In this paper, we will analyse the cosmological models in Einstein-aether gravity, which is a modified theory of gravity in which a time-like vector field breaks the Lorentz symmetry. We will use this formalism to analyse different cosmological models with different behavior of the scale factor. In this analysis, we will use a certain functional dependence of the dark energy on the Hubble parameter. It will be demonstrated that the aether vector field has a non-trivial effect on these cosmological models. We will also perform the \emph{Om} diagnostic in Einstein-aether gravity. Thus, we will fit parameters of the cosmological models using recent observational data.

gr-qc↗

arXiv2016

Power-Law Entropy-Corrected Holographic Dark Energy in Hořava-Lifshitz Cosmology with Granda-Oliveros Cut-off

In this paper, we study the Power Law Entropy Corrected Holographic Dark Energy (PLECHDE) model in the framework of a non-flat Universe and of Hořava-Lifshitz cosmology with infrared cut-off given by recently proposed Granda-Oliveros cut-off, which contains one term proportional to the Hubble parameter squared $H^2$ and one term proportional to the first time derivative of the Hubble parameter $\dot{H}$. Moreover, this cut-off is characterized by two constant parameters, $α$ and $β$. For the two cases corresponding to non-interacting and interacting DE and Dark Matter (DM), we derive the evolutionary form of the energy density of DE $Ω_D'$, the Equation of State (EoS) parameter of DE $ω_D$ and the deceleration parameter $q$. Using the parametrization of the EoS parameter $ω_D\left(z\right)=ω_0+ω_1 z$, we obtain the expressions of the two parameters $ω_0$ and $ω_1$. We also study the statefinder parameters $\left\{ r,s \right\}$, the snap and lerk cosmographic parameters and the squared speed of the sound $v_s^2$. We also calculate the values of the quantities we study for different values of the running parameter $λ$ and for different set of values of $α$ and $β$.

gr-qc↗

arXiv2016

Power-law and Logarithmic Entropy Corrected Holographic Dark Energy Models in Brans-Dicke Cosmology with Granda-Oliveros Cut-Off

In this paper, the cosmological implications of the Power Law Entropy Corrected Holographic Dark Energy (PLECHDE) and the Logarithmic Entropy Corrected Holographic Dark Energy (LECHDE) models in the context of Brans-Dicke (BD) cosmology for both non-interacting and interacting DE and Dark Matter (DM) are studied. As the system infrared cut-off, we choose the recently proposed Granda-Oliveros cut-off, which contains a term proportional to the first time derivative of the Hubble parameter and one term proportional to $H^2$, i.e. the Hubble parameter squared. We obtain the expressions of three quantities, i.e. the Equation of State (EoS) parameter $ω_D$, the deceleration parameter $q$ and the evolutionary form of the energy density parameter $Ω'_D$ of the PLECHDE and LECHDE models in a non-flat Universe for non-interacting and interacting DE and DM as well. Moreover, we investigate the limiting cases corresponding to: a) absence of entropy corrections; b) Einstein's gravity; and c) concomitantly absence of entropy corrections and Einstein's gravity. Furthermore, we consider the limiting case corresponding to the Ricci scale, which is recovered for some particular values of the parameters characterizing the Granda-Oliveros scale. We also study the statefinder diagnostic and the cosmographic parameters for both models considered in this work.

physics.gen-ph↗

arXiv2015

Consequences of three modified forms of holographic dark energy models in bulk-brane interaction

In this paper, we study the effects which are produced by the interaction between a brane Universe and the bulk in which the Universe is embedded. Taking into account the effects produced by the interaction between a brane Universe and the bulk, we derived the Equation of State (EoS) parameter $ω_D$ for three different models of Dark Energy (DE), \emph{i.e.} the Holographic DE (HDE) model with infrared (IR) cut-off given by the Granda-Oliveros cut-off, the Modified Holographic Ricci DE (MHRDE) model and a DE model which is function of the Hubble parameter $H$ squared and to higher derivatives of $H$. Moreover, we have considered two different cases of scale factor (namely, the power law and the emergent ones). A nontrivial contribution of the DE is observed to be different from the standard matter fields confined to the brane. Such contribution has a monotonically decreasing behavior upon the evolution of the Universe for the emergent scenario of the scale factor, while monotonically increasing for the power-law form of the scale factor $a(t)$.

gr-qc↗

arXiv2014

Holographic Dark Energy Models and Higher Order Generalizations in Dynamical Chern-Simons Modified Gravity

Dark Energy models are here investigated and studied in the framework of the Chern-Simons modified gravity model. We bring into focus the Holographic Dark Energy (HDE) model with Granda-Oliveros cut-off, the Modified Holographic Ricci Dark Energy (MHRDE) model and, moreover, a model with higher derivatives of the Hubble parameter as well. The relevant expressions of the scale factor a(t) for a Friedmann-Robertson-Walker Universe are derived and studied, and in this context, the evolution of the scale factor is shown to be similar to that one displayed by the modified Chaplygin gas in two of the above models.

gr-qc↗