arXiv subjects

José Abdalla Helayël-Neto

Publications and source records attributed to José Abdalla Helayël-Neto.

11 recordsLinked to original sources

arXiv2026

Investigating planar Proca metamaterials in nonlinear (2+1)-Electrodynamics

The present work pursues the investigation of the physics of a planar electromagnetic system incorporating nonlinear effects, as well as de Broglie-Proca and Chern-Simons mass terms in vacuum, which can be tuned to describe new planar metamaterials (MTMs) potentially suitable for technological applications. As a result, we observe interesting effects generated by a spatially dispersive profile that emerges from non-linearity. This characterizes the three-dimensional QED vacuum as a nonlocal metamaterial. The constitutive relations are derived, and the dielectric function of the metamaterial (MTM) exhibits spatial dispersion due to the Chern-Simons mass. The dispersion relations are analyzed in terms of applied external electromagnetic fields and both the de Broglie-Proca and Chern-Simons mass parameters. We also notice that, in the special case in which only a background magnetic field is present, this field gives no contribution neither to the dielectric function nor to the spatial dispersion profile, as is the case when both the electric and magnetic fields are present.

physics.optics↗

arXiv2026

Stellar Bounds on a Model with Photon-Photino Oscillation

In this paper, we pursue an investigation of the consequences of a mixing between supersymmetric partners - the photon and photino - analogous to the so-called Primakoff effect, but induced by a Lorentz-symmetry violating (LSV) fermionic-condensate background. In our framework, the LSV parameters are introduced as members of a non-dynamical superfield. As a consequence, we show that naturally there appears a mixing term between the gauge boson and the gaugino, which can be readily seen in the superspace/superfield approach. We inspect the kinetic photon-photino mixing matrix in the scenario of stellar physics which we apply our results to. Bounds on the strength of the fermionic LSV background are can be set by invoking the energy loss argument and the solar data we adopt.

hep-ph↗

arXiv2024

Considerations on electromagnetic radiation in Podolsky electrodynamics within a Lorentz-symmetry violating framework

We explore how higher-order derivative terms impact a physical observable within a Lorentz-Symmetry Violating (LSV) framework. We specifically examine Podolsky electrodynamics coupled with the Carroll-Field-Jackiw model (CFJ). Our analysis shows how vacuum and wave propagation are affected by the interaction of LSV parameters with properties of Podolsky electrodynamics. In this scenario, our results indicate that the new electromagnetic vacuum is birefringent, dichroic, and dispersive. We also point out that the higher-derivative term in the presence of the CFJ space-time anisotropy induces an oscillation mechanism between the photon, which acquires a non-vanishing mass, and the massive vector mode carried by the higher derivative. We then investigate the electromagnetic radiation emitted by a moving charged particle interacting with this new medium. Our analysis reveals that the refractive vacuum through which the charged particle travels influences the electromagnetic radiation, leading to a profile similar to the Cherenkov effect.

hep-ph↗

arXiv2023

QED-vacuum response and Cherenkov radiated energy in non-linear and Lorentz-symmetry violating scenarios

We investigate physical consequences of non-linear electrodynamic coupled to parameters that signal violation Lorentz-symmetry breaking (LSV). Our undertaking is done by considering a general non-linear photonic Lagrangian which coupled to the Carroll-Field-Jackiw's model (CFJ). Our endeavor reveals how the (meta) material constitutive properties of the vacuum and wave propagation are affected by the interference of the LSV parameters LSV with the specific non-linear electrodynamic model under consideration. We also discuss the refractive indices for this new medium characterized by the coupling between non-linearities and the operators that carry the LSV message. Our results show that the QED-vacuum responds with birefringence and a dispersive propagation of waves. Subsequently, we consider the electromagnetic radiation produced by a moving charged particle interacting with this new medium. Our inspection illustrates that the emitted radiation reproduces the features of the Cherenkov effect for certain intensities of background magnetic fields . Finally, we compute the static potential profile within the framework of the gauge-invariant, but path-dependent, variables formalism. A logarithmic correction to the usual static Coulomb potential emerges driven by the LSV parameter and there also appear corrections due to the non-linearity; nevertheless, the logarithm behavior drops out whenever the LSV parameter is switched off.

hep-ph↗

arXiv2020

Spin-polarized current, spin-transfer torque and spin Hall effect in presence of an electromagnetic non-minimal coupling

In this contribution, we start off from a fully relativistic description of a single electron non-minimally coupled to an external electromagnetic field. Making direct use of the field equation, instead of canonically deriving from the Lagrangian density, the relativistic total angular momentum is attained, where the effect of the relativistic torque due to the external sources is also taken into account. Both the spin density and the orbital angular momentum tensors are identified in the relativistic-covariant approach. Furthermore, the symmetric and gauge invariant energy-momentum tensor is derived as well. In addition, to inspect the non-relativistic regime, a perturbative expansion of the field equation up to the leading order in $\left(v/c\right)$ is carried out, where spin-orbit interaction terms naturally emerge in the non-relativistic Hamiltonian as a consequence of the non-minimal coupling. Features related to the spin currents, the spin-transfer torque and their dependence on both magnetic and electric external fields are then calculated and discussed. Considering that spin-orbit coupled systems are of particular interest in the study of spin Hall effect, a two-dimensional (planar) scenario of the system is contemplated, where the contributions to the Landau levels are re-assessed. As a consequence of the planar regime and the non-minimal coupling, a peculiar sort of fractionalization of the spin-up and -down components emerges with the different spin components localized in distinct positions.

cond-mat.mes-hall↗

arXiv2019

On a Gambini-Pullin-inspired Maxwell electrodynamics with Lorentz-violating dimension-$5$ operators

We explore the properties of a new Maxwell electrodynamics coupled to a Lorentz-violating background through the presence of higher-derivative terms. Physical implications of this alternative effective theory modified by Lorentz-violating operators of mass dimension-$5$ are considered, such as modified dispersion relations which exhibit the vacuum birefringence phenomenon. Subsequently, we analyze the energy-momentum tensor in the case we reproduce the Gambini-Pullin electrodynamics. We explicitly show that for a background time-like four-vector, $n^μ$, the equations of motion indeed reproduce those encountered by Gambini and Pullin in the framework of loop quantum gravity . Finally, extended expressions for Maxwell-type equations are written down in the case the external Lorentz-violating four-vector is space-like.

hep-th↗

arXiv2018

Modified plasma waves described by a logarithmic electrodynamics

The propagation of plasma waves in a new non-linear, logarithmic electrodynamics model is performed. A cold, uniform, collisionless fluid plasma model is applied. Electrostatic waves in magnetized plasma are shown to correspond to modified Trivelpiece-Gould modes, together with changes of the plasma and upper-hybrid frequencies, driven by the logarithmic electrodynamics effects. Electromagnetic waves are described by a generalized Appleton-Hartree dispersion relation. The cases of propagation parallel or perpendicular to the equilibrium magnetic field are analyzed in detail. In particular, generalized ordinary and extraordinary modes are obtained. We determine the changes, due to logarithmic electrodynamics, in the allowable and forbidden frequency bands of the new extraordinary mode. Estimates are provided about the strength of the ambient magnetic field, so that the non-linear electrodynamics effects become decisive.

physics.plasm-ph↗

arXiv2017

Structural scale $q-$derivative and the LLG-Equation in a scenario with fractionality

In the present contribution, we study the Landau-Lifshitz-Gilbert equation with two versions of structural derivatives recently proposed: the scale $q-$derivative in the non-extensive statistical mechanics and the axiomatic metric derivative, which presents Mittag-Leffler functions as eigenfunctions. The use of structural derivatives aims to take into account long-range forces, possible non-manifest or hidden interactions and the dimensionality of space. Having this purpose in mind, we build up an evolution operator and a deformed version of the LLG equation. Damping in the oscillations naturally show up without an explicit Gilbert damping term.

math-ph↗

arXiv2016

Scalar-Interchange Potential and Magnetic/Thermodynamic Properties of Graphene-like Materials

By means of numerical simulations, we explore possible effects of a special interparticle interaction potential which is a function of external and internal conditions of graphene-like systems. In addition to the electromagnetic interaction, we introduce a new potential due to the exchange of a massive scalar, associated to the so-called Kekulé deformations; this interaction displays a spin-dependent profile. It turns out that the magnitude of Kekulé deformation may significantly affect physical properties of graphene. A Monte Carlo analysis enables one to analyze the behavior of the system under variation of the applied external field, temperature, and the particular type of the exchanged excitation that induces the potential. We pursue an investigation of the spin configurations, we analyze differences in thermal equilibrium magnetization and we carry out calculations of the magnetic susceptibility and the specific heat in the presence of the Kekulé-induced new potential.

cond-mat.mes-hall↗

arXiv2015

Variational Approach and Deformed Derivatives

Recently, we have demonstrated that there exists a possible relationship between q-deformed algebras in two different contexts of Statistical Mechanics, namely, the Tsallis' framework and the Kaniadakis' scenario, with a local form of fractional-derivative operators for fractal media, the so-called Hausdorff derivatives, mapped into a continuous medium with a fractal measure. Here, in this paper, we present an extension of the traditional calculus of variations for systems containing deformed-derivatives embedded into the Lagrangian and the Lagrangian densities for classical and field systems. The results extend the classical Euler-Lagrange equations and the Hamiltonian formalism. The resulting dynamical equations seem to be compatible with those found in the literature, specially with mass-dependent and with nonlinear equations for systems in classical and quantum mechanics. Examples are presented to illustrate applications of the formulation. Also, the conserved Nether current, are worked out.

math-ph↗

arXiv2015

On the Zitterbewegung Transient Regime in a Coarse-Grained Space-Time

In the present contribution, by studying a fractional version of Dirac's equation for the electron, we show that the phenomenon of Zitterbewegung in a coarse-grained medium exhibits a transient oscillatory behavior, rather than a purely oscillatory regime, as it occurs in the integer case, $α=1$. Our result suggests that, in such systems, the Zitterbewegung-type term related to a trembling motion of a quasiparticle is tamed by its complex interactions with other particles and the medium. This can justify the difficulties in the observation of this interesting phenomenon. The possibility that the Zitterbewegung be accompanied by a damping factor supports the viewpoint of particle substructures in Quantum Mechanics.

hep-th↗