This paper aims to discuss the gravitationally induced particle creation in the framework of f(𝒢,T) theory, which involves the non-minimal coupling (NMC) between Gauss–Bonnet (GB) invariant, 𝒢 and trace of the energy–momentum tensor (EMT), T. Here, NMC between matter and gravitational sector results in non-divergence of EMT. We discuss the generalized conservation equation for the irreversible process

A spherical planetary nebula is described as a geometric model. The nebula itself is considered as a thin-shell, which is visualized as a boundary of two spacetimes. The inner and outer curvature tensors of the thin-shell are found in order to get an expression of the energy-momentum tensor on the thin-shell. The energy density and pressure expressions are derived using the energy-momentum tensor.

The objective of this paper is to deal with Kenmotsu manifolds admitting η-Ricci-Yamabe solitons. First, it is proved that if a Kenmotsu manifold M which admits an η-Ricci-Yamabe soliton, then the manifold M is Einstein and is of constant scalar curvature. Then, some important characterizations, which classify Kenmotsu manifolds admitting such solitons, are obtained and an example given which supports

In this work, we revisit the shear-free conjecture of general relativity and study the well-known shear-free condition in the context of the Chaplygin-gas cosmology. It had been shown in previous investigations that, in the general relativistic framework, the matter congruences of shear-free perfect fluid spacetimes should be either expansion-free or rotation-free. Our current investigation, however

In this work, we study the modified Klein–Gordon oscillator by replacing the momentum vector p→→(p→−iMΩf(r)r̂) in the Klein–Gordon equation under scalar and electromagnetic potentials in a rotating cosmic string space-time. The electromagnetic and scalar potentials are chosen to be proportional to the inverse of the axial distance (∝1r). We solve the radial wave equation and obtain the energy eigenvalues

In this work, a new model of double-Logarithmic electrodynamics has been minimally coupled to Einstein-massive gravity and the nonlinearly charged black holes in the presence of quintessential cosmic dark energy and string cloud background are investigated. In this set up, new magnetically charged black hole solution has been derived. Thermodynamics of these black holes are also analyzed and different

We review different approaches to the Hamiltonian analysis of teleparallel theories of gravity. In particular, the Hamiltonian analysis for f(𝕋) theories led to disputed results in the literature. The aim of this review is to relate the different notations and assumptions in the different approaches in a comprehensive way, so that they can be compared more easily. To do this we present the primary

In this paper, we attempt to introduce a new approach to determine the magnetic helicity and energy dissipation of the normal electromagnetic vortex filaments in magnetohydrodynamics (MHD). We successfully compute the vector potential and magnetic helicity of Frenet–Serret vectors and associated electromagnetic fields in the existence of the Lorentz force. We further describe a set of differential

We study a relation between certain extensions of the Clifford bundle and Finsler type structures that naturally generalize the standard Clifford relation between (pseudo)-Riemannian metric structures and Dirac matrices. We show for flat metrics that there is a triangle map between Finsler structures constructed from a (pseudo)-Riemannian metric and 1-forms on M, the extension of the Clifford bundle

In this paper, we study almost coKähler manifolds admitting k-almost Yamabe solitons (g,V,k,λ). First, we obtain a classification of almost coKähler (κ,μ)-manifolds admitting nontrivial closed k-almost Yamabe solitons. Next, we consider an almost α-coKähler manifold admitting a nontrivial k-almost Yamabe soliton and prove that it is locally the Riemannian product of an almost Kähler manifold with the

In this paper, we study almost quasi-Yamabe solitons and gradient almost quasi-Yamabe solitons in 3-dimensional f-Kenmotsu manifolds.

In this paper, we discuss thermodynamics for spherically symmetric and static traversable wormholes which include Morris–Thorne wormholes and charged wormholes in the background of f(R,T) gravity. The local coordinates have been used to find trapping horizons of these objects and generalized surface gravity has been worked out on the trapping horizons. The expression for the unified first law has also

The geometric intrinsic approach to Hojman symmetry is developed and use is made of the theory of the Jacobi last multipliers to find the corresponding conserved quantity for non divergence-free vector fields. The particular cases of autonomous Lagrangian and Hamiltonian systems are studied as well as the generalization of these results to normalizer vector fields of the dynamics. The nonautonomous

In this paper, we discuss about a set of geometric and physical properties of hyper-generalized quasi-Einstein spacetime. In the beginning, we discuss about pseudosymmetry over a hyper-generalized quasi-Einstein spacetime. Here, we discuss about W2-Ricci pseudosymmetry, Z-Ricci pseudosymmetry, Ricci pseudosymmetry and projective Ricci pseudosymmetry over a hyper-generalized quasi-Einstein spacetime

In this paper, we deal with the Dirac equation and angular momentum, which have an important place in physics in terms of elliptic biquaternions. Thanks to the elliptic biquaternionic representation of angular momentum, we have expressed some useful mathematical and physical results. We obtain the solutions of the Dirac equation with the help of Dirac matrices with elliptic biquaternionic structure

In this paper, we propose the generalized description of electromagnetism and linear gravity based on the combined dual numbers and complex quaternion algebra. In this approach, the electromagnetic and gravitational fields can be considered as the components of one combined dual-complex quaternionic field. It is shown that all relations between potentials, field strengths and sources can be formulated

In this paper, we first introduce a new notion β-tensor on Hermitian manifold and particularly, we present some geometric characterizations of such a tensor on the Kaehler manifold. Here, we investigate the Kaehler submersion whose total space is equipped with the β-tensor and obtain some results. Also, we deal with a Kaehler submersion with totally geodesic fibers such that the total space admits

In this paper, we analyze a few physical characteristics of gravastar with cylindrical geometry in f(R,T) theory, where R is the Ricci scalar and T is the trace of energy-momentum tensor. The gravastar is generally considered to be a substitute of a black hole with three different regions. In this work, we examine the formulation of gravastar-like cylindrical structures in f(R,T) theory. By using Darmois

The present work is focused on the study of traversable wormholes, proposed by Morris and Thorne [Wormholes in spacetime and their use for interstellar travel: A tool for teaching general relativity, Am. J. Phys.56 (1988) 395], using the background of modified gravity. It is performed by using the models: I. f=R+2βT, II. f=R+αRn and III. f=R+αRn+2βT, where α, β and n are constants. The Model I belongs

Electron microscopy images of decagonal quasicrystals obtained recently have been shown to be related to cluster coverings with a Hexagon–Bow–Tie decagon as single structural unit. Most decagonal phases show more complex structural orderings than models based on deterministic tilings like the Penrose tiling. We analyze different types of decagonal random tilings and their coverings by a Hexagon–Bow–Tie

In this paper, we considered an axion F(R) gravity model and described, with the help of holographic principle, the cosmological models of viscous dark fluid coupled with axion matter in a spatially flat Friedmann–Robertson–Walker (FRW) universe. This description based on generalized infrared-cutoff holographic dark energy was proposed by Nojiri and Odintsov. We explored the Little Rip, the Pseudo

In this contribution, we consider the well-known equivalence between f(R) gravity and Brans–Dicke-type scalar–tensor theories to study the evolution of scalar cosmological perturbations for a class of shear-free cosmological dust models with irrotational fluid flows. We use the 1+3 covariant formalism to present the covariant linearized evolution and constraint equations. We then derive the integrability

This work discusses about the existence of compact star model in the context of f(R,T) gravity with R as the Ricci scalar and T as the trace of energy–momentum tensor Tμν. The model has been developed by considering the spherically symmetric spacetime consisting of isotropic fluid with f(R,T)=R+2βT with β be the coupling parameter. The corresponding field equations are solved by choosing the well-known

In this paper, we discuss a new way to get a quantum holonomy around topological defects in C60 fullerenes. For this, we use a Kaluza–Klein extra dimension approach. Furthermore, we discuss how an extra dimension could promote the formation of new freedom degrees which would open a discussion about a possible qubits computation.

In this paper, we investigate the dynamical behavior of the planar polynomial system which describes the evolution of the isotropic star. It is shown that the system has no global C∞ and no global analytic first integrals. It has an invariant algebraic curve with algebraic multiplicity 1 and an exponential factor that comes from the multiplicity of the infinite invariant straight line. It is proved

In this paper, we have studied the dynamical aspects of some cosmological models in an isotropic space-time within the framework of an extended gravity theory. Two accelerating cosmological models are presented with quasi-de Sitter (QDS) and linear combination of exponential (LCE) scale factors. The geometrical testing mechanism has been performed and analyzed. While the results of the QDS model show

The purpose of this paper is to study anti-invariant Riemannian submersions from Sasakian manifolds onto Riemannian manifolds such that characteristic vector field is vertical or horizontal vector field. We first show that any anti-invariant Riemannian submersions from Sasakian manifold is not a Riemannian submersion with totally umbilical fiber. Then we introduce anti-invariant Riemannian submersions

Xu et al. (Eur. Phys. J. C79 (2019) 708) have anticipated the theory of Gravity. The modified study of f(Q,T) is elucidated here as Cosmological model. In it the action holds a role as a capricious arbitrary function f(Q,T). At this juncture Q functions as non-metricity and for matter fluid, T outlines as energy-momentum tensor. The function f(Q,T) quadratic in Q and linear in T as f(Q,T)=αQ+βQ2+γT

This paper studies the nature of fractional linear transformations in a general relativity context as well as in a quantum theoretical framework. Two features are found to deserve special attention: the first is the possibility of separating the limit-point condition at infinity into loxodromic, hyperbolic, parabolic and elliptic cases. This is useful in a context in which one wants to look for a correspondence

In this paper, we review how an algebraic formulation for the dynamics of a physical system allows to describe a reduction procedure for both classical and quantum evolutions.

The new tetrads introduced previously for non-null electromagnetic fields in Einstein–Maxwell spacetimes enable a direct link to the local electromagnetic gauge group of transformations. Due to the peculiar elements in the construction of these new tetrads, a direct connection can be established between the local group of electromagnetic gauge transformations and local groups of tetrad transformations

In this paper, an algebraic classification of the Roter type spacetimes is given. It follows that the Roter type curvature condition is essentially equivalent with the pseudosymmetry condition on 4-dimensional Lorentzian manifolds.

In this paper, we present a study of a fifth-order nonlinear partial differential equation, which was recently introduced in the literature. This equation can be used as a model for bidirectional water waves propagating in a shallow medium. Using elements of an optimal system of one-dimensional subalgebras, we perform similarity reductions culminating in analytic solutions. Rational, hyperbolic, power

In the contest of open quantum systems, we study a class of Kraus operators whose definition relies on the defining representation of the symmetric groups. We analyze the induced orbits as well as the limit set and the degenerate cases.

This paper aims at additional symmetries of the unextended and extended, commutative and noncommutative dispersionless Gelfand–Dickey (dGD) hierarchies. Being similar to the Lax formalism of the Gelfand–Dickey (GD) hierarchy, we construct the function ℒ and Orlov–Schulman function ℳ of the hierarchies. Meanwhile, the additional symmetry will be studied with the infinite flows of vi and τ function of

In the work reported here we have considered Barrow holographic dark energy (BHDE) proposed in E. N. Saridakis, Barrow holographic dark energy, Phys. Rev. D102 (2020) 123525 as a special case of more generalized version of Nojiri–Odintsov holographic dark energy (NOHDE) proposed in S. I. Nojiri and S. D. Odintsov, Unifying phantom inflation with late-time acceleration: Scalar phantom–non-phantom transition

This study explores the interior geometry of static relativistic charged spheres in the background of a recently proposed modified f(G,T) gravity, where G and T are the Gauss–Bonnet (GB) invariant and trace of energy–momentum tensor, respectively. The GB gravity is the low-energy limit of superstring theories. The structures of specific relativistic charged spheres Vela X−1, SAXJ1808.4−3658, and 4U1820−30

Recently, the inverse electrodynamics model (IEM) was introduced and applied to find Reissner–Nordström black holes in the context of the general relativity coupled minimally with the nonlinear electrodynamics. The solution consists of both electric and magnetic fields as of the dyonic solutions. Here, in this note, we show that the IEM model belongs to a more general class of the nonlinear electrodynamics

We propose a simple analytical model for Harmonic oscillator potential that is associated to the generalized uncertainty principle (GUP) in the presence of energy-dependent mass. A formal condition connected with these systems is based on the mathematical structure of modified quantum mechanics. Consequently, thanks to Feynman’s path integrals formalism, we are able to treat the reorganization of wave

Implications of the Raychaudhuri equation in focusing of geodesic congruences are studied in the framework of scalar–tensor theory of gravity. Specifically, we investigate the Brans–Dicke theory and Bekenstein’s scalar field theory. In both of these theories, we deal with a static spherically symmetric distribution and a spatially homogeneous and isotropic cosmological model as specific examples. We

We construct a new class of d-dimensional black hole solutions with Toroidal horizons in f(R) gravity framework which is surrounded by quintessence and string cloud configuration, whose asymptotic structures are determined by the quintessential state parameter ωq and dimension’s parameter d. We point out that the asymptotic behavior of the obtained solutions is neither asymptotically flat nor (A)dS

In this paper, we construct a new approach of spherical magnetic Lorentz flux of spherical 𝕊α-magnetic flows of particles by the spherical frame in 𝕊2 spherical space. Eventually, we obtain some optical conditions of spherical 𝕊α-magnetic Lorentz flux by using directional spherical fields. Moreover, we determine spherical magnetic Lorentz flux for spherical vector fields. Also, we give new construction

In this paper, we will show that a power law asymptotic de Sitter inflation will be established for all values of Hankel indices ν that relate to the different background spacetimes of the universe in their evolution. First, we calculate the relations for the Hubble, deceleration, slow roll and the equation of state parameters in terms of the Hankel function index ν. We then show that the obtained

This article is based on the extension of Teleparallel Theory named f(τ,T) gravity, where the notions τ and T abbreviate the torsion trace term of the energy–momentum tensor. This study aims to explore the anisotropic outcomes of the VelaX−1 model. We use the field equations drawn by using the spherical symmetry, including the torsion trace term. The major components grr and gtt, of spherical symmetric

We study the dynamics and redistribution of entanglement and coherence in three time-dependent coupled harmonic oscillators. We resolve the Schrödinger equation by using time-dependent Euler rotation together with a linear quench model to obtain the state of vacuum solution. Such state can be translated to the phase space picture to determine the Wigner distribution. We show that its Gaussian matrix

In this paper, we consider homothetic Killing vectors in the class of stationary axisymmetric vacuum (SAV) spacetimes, where the components of the vectors are functions of the time and radial coordinates. In this case, the component of any homothetic Killing vector along the z direction must be constant. First, it is shown that either the component along the radial direction is constant or we have

In this paper, we introduce new frame and new transformation associated with combined Korteweg–de Vries–modified Korteweg–de Vries (KdV–mKdV) equation, the mKdV and the KdV equations with respect to the null Cartan frame in Minkowski 3-space. Direction of the state of polarization of monochromatic linear polarized light wave traveling in the optic fiber is given by the direction of electric field vector

The aim of this paper is to classify locally rotationally symmetric (LRS) Bianchi type I space-times via conformal vector fields (CVFs) in the f(T,B) gravity. In a first step, we find the space-times that are solutions of some f(T,B) gravity model. Furthermore, we classify the resulting space-times via CVFs. During the classification, there arise eight cases. Reviewing each case thoroughly, we find

In this study, we have investigated the dark energy behavior of the viscus-fluid in f(Q)-gravity in a flat, isotropic and homogeneous Friedmann–Lemaitre–Robertson–Walker (FLRW) space-time metric. We have considered the linear form of f(Q) function as f(Q)=−αQ−β with α>0 and β>0 as model parameters. We have solved the field equations for the scale factor a(τ) and found a(τ)=c1[sinh(k2τ)]k3, where k

We study null hypersurfaces of a Lorentzian manifold with a closed rigging for the hypersurface. We derive inequalities involving Ricci tensors, scalar curvature, squared mean curvatures for a null hypersurface with a closed rigging of a Lorentzian space form and for a screen homothetic null hypersurface of a Lorentzian manifold. We also establish a generalized Chen–Ricci inequality for a screen homothetic

Leading order study of direct photon production from proton–proton collisions, in the framework of Minimal (Seiberg–Witten) Non-Commutative Standard Model (NCSM), taking into account the Earth-rotation effects. We found that relative non-commutative contributions increase significantly at very high photon transverse momentum. Therefore, using Run-1 (√s=8 TeV) and Run-2 (√s=13 TeV) ATLAS experimental

We present an information geometric analysis of both entropic speeds and entropy production rates arising from geodesic evolution on manifolds parametrized by pure quantum states. In particular, we employ pure states that emerge as outputs of suitably chosen su(2;ℂ) time-dependent Hamiltonian operators that characterize analog quantum search algorithms of specific types. The su(2;ℂ) Hamiltonian models

The object of the paper is to study the compatibility of φ(Ric)-vector fields on almost pseudo-Ricci symmetric manifolds, briefly A(PRS)n. First, we show the existence of an A(PRS)n whose basic vector field w(X) is a φ(Ric)-vector field by constructing a non-trivial example. Then, we investigate the properties of the Riemann and Weyl compatibility of A(PRS)n under certain conditions. We consider an

We discuss the possible role of the Tietze extension theorem in providing a rigorous topological base to the expanding space-time in cosmology. A simple toy model has been introduced to show the analogy between the topological extension from a circle S to the whole space M and the cosmic expansion from a non-zero volume to the whole space-time in non-singular cosmological models. A topological analogy

In this paper, we study two different cases of inhomogeneous EOS of the form pd=w(t)ρd+w1f(H,t). We derive the energy density of dark fluid and dark matter component for both the cases. Further, we calculate the evolution of energy density, gravitational constant and cosmological constant. We also explore the finite time singularity and thermodynamic stability conditions for the two cases of EOS. Finally

There are two smooth functions σ and ρ associated to a nontrivial concircular vector field v on a connected Riemannian manifold (M,g), called potential function and connecting function. In this paper, we show that presence of a timelike nontrivial concircular vector field influences the geometry of generalized Robertson–Walker space-times. We use a timelike concircular vector field v on an n -dimensional

In this paper, we investigate a feasible holography with the Kitaev model using dilatonic gravity in AdS2. We propose a generic dual theory of gravity in the AdS2 and suggest that this bulk action is a suitable toy model in studying quantum mechanics in Kitaev model using gauge/gravity duality. This gives a possible equivalent description for the Kitaev model in the dual gravity bulk. Scalar and tensor

In this paper, evolution of a Friedmann–Robertson–Walker universe is studied in a higher derivative theory of gravity. The relativistic solutions admitting hybrid expansion law of the universe are explored here. Hybrid expansion law is a general form of scale factor from which one can recover both the power-law expansion and exponential expansion as a special case. The hybrid expansion law is interesting

In this paper, traversable wormholes have been studied in f(R)=R+αRm+βR−n gravity, where α, β, m>0 and n>0 are constant. A simplest form of shape function and a logarithmic form of redshift function is considered to construct wormhole solutions. The range of parameters providing the wormhole solutions free from the matter violating the energy conditions is explored. Further, the effect of charge is

In this paper, we construct metallic Kähler and nearly metallic Kähler structures on Riemannian manifolds. For such manifolds with these structures, we study curvature properties. Also, we describe linear connections on the manifold which preserve the associated fundamental 2-form and satisfy some additional conditions and present some results concerning them.