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P. Castelo Ferreira

Publications and source records attributed to P. Castelo Ferreira.

At least 19 recordsLinked to original sources
arXiv2018

Comments on "Vacuum Birefringence in a Rotating Magnetic Field" [S. L. Adler, J. Phys. A40 (2007) F143-F152] and "The Rotation of magnetic field does not impact vacuum birefringence" [S. Biswas and K. Melnikov, Phys. Rev. D75 (2007) 053003]

Compilation of 2 comments on S. L. Adler, "Vacuum Birefringence in a Rotating Magnetic Field", J.Phys. A40 (2007) F143-F152, hep-ph/0611267 and S. Biswas and K. Melnikov, "The Rotation of magnetic field does not impact vacuum birefringence", Phys. Rev. D75 (2007) 053003, hep-ph/0611345, hope it has some usefulness.

hep-ph↗
arXiv2018

Parameterizing the flattening of galaxies rotation curves on an expanding locally anisotropic background

In this paper are discussed possible many body generalizations of the expanding locally anisotropic metric ansatz with respect to approximately Newtonian gravitational systems. This ansatz consistently describes local point-like matter distributions on the expanding Universe also allowing for a covariant parameterization of gravitational interactions at intermediate length scales. As an example of applicability it is modeled a disk galaxy model matching the physical parameters of the galaxy UGC2885 and it is shown that, by fine-tuning the metric functional parameter, the flattening of the galaxy rotation curve is fully parameterized by this metric. In addition it is numerically computed the mass-energy density corrections due to the expanding anisotropic background and explicitly shown that although there are negative contributions within the galaxy plane the total mass-energy density is strictly positive both at the galaxy plane and outside the galaxy plane. As the functional parameter for this metric is an exponential factor is required a floating point precision of $250$ significant digits for root finding routines and $200$ significant digits to evaluate the effective mass-energy density rendering a final precision of the results presented above double precision ($16$ significant digits). It is further shown that these results are consistent with the interpretation of the gravitational corrections as due to Dark Matter, in particular constituting a novel heuristic local parameterization for the Dark Matter distribution within the galaxy plane consistent with both local scale and cosmological scale physical laws which is useful to further investigate the local properties of Dark Matter.

astro-ph.CO↗
arXiv2018

Rotating Magnetic Solutions for 2+1D Einstein Maxwell Chern-Simons

In this article are computed magnetic solutions of Einstein Maxwell Chern-Simons theory coupled to a dilaton-like scalar field. These solutions are computed by applying a space-time duality suggested by the author to known electric solutions of the same theory. As a redundancy check for the space-time duality it is explicitly shown that the magnetic configurations obtained are, as expected, solutions of the equations of motion. The magnetic configurations have metric determinant $\sqrt{-g}\sim r^p$ for the range of the parameter $p\in]-\infty,+\infty[/\{-1\}$ and are interpreted either as magnetic string-like configurations, configurations driven by an externally applied magnetic field or cosmological-like solutions with background magnetic fields.

gr-qc↗
arXiv2018

Electro-Magnetic Space-Time Duality for 2+1-Dimensional Stationary Classical Solutions

In this paper it is studied a space-time duality web that maps electric into magnetic (and magnetic into electric) charged classical stationary rotating solutions for $2+1$-dimensional Abelian Einstein Maxwell Chern-Simons theories. A first duality map originally suggested by Kogan for static charged solutions is extended to stationary rotating space-times and are suggested two new space-time dualities maps. The three dualities complete a close duality web. It is also shown that in $3+1$-dimensions these dualities are only possible for systems which exhibit non-projected cylindrical symmetry and are not related to the standard electromagnetic duality of Maxwell equations which acts on the physical fields and charges. Generalization to $N$-form theories in higher dimensional space-times is briefly discussed.

hep-th↗
arXiv2017

Planetary motion on an expanding locally anisotropic background

In this work are computed analytical solutions for orbital motion on a background described by an Expanding Locally Anisotropic (ELA) metric ansatz. This metric interpolates between the Schwarzschild metric near the central mass and the Robertson-Walker metric describing the expanding cosmological background far from the central mass allowing for a fine-tuneable covariant parameterization of gravitational interactions corrections in between these two asymptotic limits. In particular it is shown that the decrease of the Sun's mass by radiation emission plus the General Relativity corrections due to the ELA metric background with respect to Schwarzschild backgrounds can be mapped to the reported yearly variation of the gravitational constant $\dot{G}$ through Kepler's third law. Based on the value of the heuristic fit corresponding to the more recent heliocentric ephemerides of the Solar System are derived bounds for the value of a constant parameter $α_0$ for the ELA metric as well as the maximal corrections to perihelion advance and orbital radii variation within this framework. Hence it is shown that employing the ELA metric as a functional covariant parameterization to model gravitational interactions corrections within the Solar System allows to maintain the measurement projection standards constant over time, specifically both the Astronomical Unit ($AU$) and the Gravitational constant ($G$). Also it is noted that the effect obtained is not homogeneous for all planetary orbits consistently with the diversity of estimates in the literature obtained assuming Schwarzschild backgrounds.

gr-qc↗
arXiv2012

Constraining an Expanding Locally Anisotropic metric from the Pioneer anomaly

It is discussed the possibility of a fine-tuneable contribution to the two way Doppler acceleration either towards, either outwards the Sun for heliocentric distances above 20 AU by considering a background described by an Expanding Locally Anisotropic (ELA) metric. This metric encodes both the standard local Schwarzschild gravitational effects and the cosmological Universe expansion effects allowing simultaneously to fine-tune other gravitational effects at intermediate scales, which may be tentatively interpreted as a covariant parameterization of either cold dark matter either gravitational interaction corrections. Are derived bounds for the ELA metric functional parameter by considering the bounds on the deviation from standard General Relativity imposed by the current updated limits for the Pioneer anomaly, taking in consideration both the natural outgassing and on-board radiation pressure, resulting in an average Doppler acceleration outwards the Sun of a_p = +0.4^{+2.1}_{-2.0} x 10^{-10} (m/s^2). It is also computed the mass-energy density for the ELA metric within the bounds obtained and are discussed the respective contributions to the cosmological mass-energy density which, for compatibility with the Lambda-CDM model, are included in Omega_{CDM}.

gr-qc↗
arXiv2012

Landau-Ginzburg Chern-Simons model with Ue(1)xUg(1) Gauge Symmetry and Internal Pseudo-Photons

In this article it is studied, at variational level, a mathematical setup given by the Landau-Ginzburg Chern-Simons model for anyons in 2+1-dimensions within the framework of dimensional reduced Ue(1)xUg(1) extended electromagnetism with both vector gauge fields (photons) and pseudo-vector gauge fields (pseudo-photons) such that both magnetic and electric vortexes coexist in the planar system. This model exhibits explicit planar P and T discrete symmetries being the Hall conductivity consistently a tensor and the Dirac quantization on the electric and magnetic coupling constants is equivalent to the quantization of magnetic flux. It is also discussed a thickening to 4-dimensions of the model with explicit 4-dimensional P violation which allows either for electric and magnetic charge separation, either for the Meissner effect. Although mathematically consistent, the electromagnetic field content for this model does not coincide with the standard Hall effect being present an extra orthogonal electric and longitudinal magnetic fields.

hep-th↗
arXiv2012

Effective Fractional Hall Effect with Pseudo-Photons

At variational level in the framework of dimensional reduced 'U_e(1)\times U_g(1)' electromagnetism it is considered an anyon Landau-Ginzburg Chern-Simons model for the fractional Hall effect. The collective gauge fields are due to pseudo-photons (...). We show that the model contains both magnetic vortexes due to the internal photons (interpreted as quasi-particles) and electric vortexes due to the internal pseudo-photons (interpreted as quasi-holes) that account for the anyon quantized magnetic flux and fractional electric charges, respectively. The effective magnetic flux is the only effective effect attributed to the standard internal photon which ensures compatibility between the pseudo nature of Laughlin's wave functions and macroscopical parity 'P' and time-inversion 'T' symmetries. In this way the model preserves these symmetries both at variational level and at the level of the electromagnetic equations. In particular holds the usual fractional Hall conductances with the Hall conductance '\hatσ_H' being a pseudo-scalar consistently with the electric Hall current equation. The negative energy contribution of quasi-holes to the Laughlin's wave function (...) is justified and the quantization of magnetic flux is directly equivalent to the Dirac's quantization condition applied to the coupling constants, or fundamental unit charges 'e' and 'g'. If our framework proves to be correct, quantization of magnetic flux may be the most direct evidence for Dirac's quantization condition. Our results also indicate that pseudo-photons electric vortex may give a theoretical justification for the electric potential between layers of bi-layer Hall systems.

hep-th↗
arXiv2011

A heuristic solution for the Pioneer anomaly employing an ELA metric with dark matter in the outskirts of the Solar system

Considering an expanding locally anisotropic (ELA) metric with the Sun as central mass and the heuristic ansatz for the dimensionless functional exponent parameter 'alpha=3+alpha_2(r_1)(1-U_Sun)^2' with a linear ansatz 'alpha_2(r_1)=alpha_2^(2.0)+alpha_2^(2.1) r_1' above 20 AU the pioneer anomaly is fully accounted for as due to the blue-shift of the background space-time. For compatibility with orbital motion within the Solar system it is further considered a branch ansatz for which α_2(r_1)=0 below 20 AU. This construction reduces the physical acceleration correction above 20 AU down to ~10^(-14) m/s^2 outwards from the Sun such that orbital corrections to Neptune and Pluto are less notorious than when the full Pioneer acceleration is considered to be a gravitational acceleration. It is also discussed the effective mass-energy density distribution above 20 AU due to the background corrections, the respective equation of state ('-1 < w < -0.726') and the finite non-null total mass is computed by considering an upper cut-off for the functional parameter 'alpha'. Such effective extended configuration is tentatively interpreted as a cold dark matter distribution.

gr-qc↗
arXiv2010

An Expanding Locally Anisotropic (ELA) Metric Describing Matter in an Expanding Universe

It is suggested an expanding locally anisotropic metric (ELA) ansatz describing matter in a flat expanding universe which interpolates between the Schwarzschild (SC) metric near point-like central bodies of mass 'M' and the Robertson-Walker (RW) metric for large radial coordinate: 'ds^2=Z(cdt)2 - 1/Z (dr1-(Hr1/c) Z^(alpha/2+1/2)(cdt))^2-r1^2 dOmega', where 'Z=1-U' with 'U=2GM/(c^2r1)', 'G' is the Newton constant, 'c' is the speed of light, 'H=H(t)=\dot(a)/a' is the time-dependent Hubble rate, 'dOmega=dtheta^2+sin^2(theta) dvarphi^2' is the solid angle element, 'a' is the universe scale factor and we are employing the coordinates 'r1=ar', being 'r' the radial coordinate for which the RW metric is diagonal. For constant exponent 'alpha=alpha0=0' it is retrieved the isotropic McVittie (McV) metric and for 'alpha=alpha0=1' it is retrieved the locally anisotropic Cosmological-Schwarzschild (SCS) metric, both already discussed in the literature. However it is shown that only for constant exponent 'alpha=alpha0> 1' exists an event horizon at the SC radius 'r1=2GM/c^2' and only for 'alpha=alpha0>= 3' space-time is singularity free for this value of the radius. These bounds exclude the previous existing metrics, for which the SC radius is a naked extended singularity. In addition it is shown that for 'alpha=alpha0>5' space-time is approximately Ricci flat in a neighborhood of the event horizon such that the SC metric is a good approximation in this neighborhood. It is further shown that to strictly maintain the SC mass pole at the origin 'r1=0' without the presence of more severe singularities it is required a radial coordinate dependent correction to the exponent 'alpha(r1)=alpha0+alpha1 '2GM/(c^2 r1)' with a negative coefficient 'alpha1<0'. The energy-momentum density, pressures and equation of state are discussed.

gr-qc↗
arXiv2009

A Locally Anisotropic Metric for Matter in an Expanding Universe: I. The Ansatz and the Modified Newton Law

It is suggested a metric ansatz to describe local matter in an expanding universe, hence interpolating between the Schwarzschild metric at small spatial scales and the FLRW metric at large spatial scales. This is acomplished maintaining space-time free of singularities except for the Schwarzschild mass pole at the origin as opposed to metrics already considered in the literature with the same purpose, namely the McVittie metric. The modified Newton law is analyzed and the static orbit solutions computed. It is concluded that the effects of expantion in the solar system are negligible, however depending on the metric parameter value, at galactic scales there is a significant deviation from the General Relativity Newton law which may contribute to dark matter effects allowing for a flattening of galaxy rotation curves.

astro-ph.CO↗
arXiv2009

Canonical Functional Quantization of Pseudo-Photons in Planar Systems

Extended $U_e(1)\times U_g(1)$ electromagnetism containing both a photon and a pseudo-photon is introduced at variational level and is justified by the violation of the Bianchi identities in conceptual systems, either in the presence of magnetic monopoles or non-regular external fields, not being accounted by the standard Maxwell Lagrangian. It is carried a dimensional reduction that renders a $U_e(1)\times U_g(1)$ Maxwell-BF type theory and it is considered canonical functional quantization in planar systems which may be relevant in Hall systems.

hep-th↗
arXiv2009

Mass for Plasma Photons from Gauge Symmetry Breaking

We derive the effective masses for photons in unmagnetized plasma waves using a quantum field theory with two vector fields (gauge fields). In order to properly define the quantum field degrees of freedom we re-derive the classical wave equations on light-front gauge. This is needed because the usual scalar potential of electromagnetism is, in quantum field theory, not a physical degree of freedom that renders negative energy eigenstates. We also consider a background local fluid metric that allows for a covariant treatment of the problem. The different masses for the longitudinal (plasmon) and transverse photons are in our framework due to the local fluid metric. We apply the mechanism of mass generation by gauge symmetry breaking recently proposed by the authors by giving a non-trivial vacuum-expectation-value to the second vector field (gauge field). The Debye length $λ_D$ is interpreted as an effective compactification length and we compute an explicit solution for the large gauge transformations that correspond to the specific mass eigenvalues derived here. Using an usual quantum field theory canonical quantization we obtain the usual results in the literature. Although none of these ingredients are new to physicist, as far as the authors are aware it is the first time that such constructions are applied to Plasma Physics. Also we give a physical interpretation (and realization) for the second vector field in terms of the plasma background in terms of known physical phenomena. Addendum: It is given a short proof that equation (10) is wrong, therefore equations (12-17) are meaningless. The remaining results are correct being generic derivations for nonmagnetized plasmas derived in a covariant QFT framework.

hep-th↗
arXiv2008

Effect of Pions in Cosmic Rays

The effects of pions for vacuum polarization in background magnetic fields are considered. The effects of quark condensates is also briefly addresses. Although these effects are out of the measurement accuracy of laboratory experiments they may be relevant for gamma-ray burst propagation. In particular, for emissions from the center of the galaxy, we show that the mixing between the neutral pion and photons results in a deviation of the gamma-ray spectrum from the standard power-law in the TeV range.

hep-ph↗
arXiv2008

QCD Corrections to QED Vacuum Polarization

We compute QCD corrections to QED calculations for vacuum polarization in background magnetic fields. Formally, the diagram for virtual $e\bar{e}$ loops is identical to the one for virtual $q\bar{q}$ loops. However due to confinement, or to the growth of $α_s$ as $p^2$ decreases, a direct calculation of the diagram is not allowed. At large $p^2$ we consider the virtual $q\bar{q}$ diagram, in the intermediate region we discuss the role of the contribution of quark condensates $\left< q\bar{q}\right>$ and at the low-energy limit we consider the $π^0$, as well as charged pion $π^+π^-$ loops. Although these effects seem to be out of the measurement accuracy of photon-photon laboratory experiments they may be relevant for $γ$-ray burst propagation. In particular, for emissions from the center of the galaxy (8.5 kpc), we show that the mixing between the neutral pseudo-scalar pion $π_0$ and photons renders a deviation from the power-law spectrum in the $TeV$ range. As for scalar quark condensates $\left< q\bar{q} right>$ and virtual $q\bar{q}$ loops are relevant only for very high radiation density $\sim 300 MeV/fm^3$ and very strong magnetic fields of order $\sim 10^{14} T$.

hep-ph↗