arXiv subjects

E. Rodriguez Querts

Publications and source records attributed to E. Rodriguez Querts.

14 recordsLinked to original sources

arXiv2014

The photon magnetic moment problem revisited

The photon magnetic moment for radiation propagating in magnetized vacuum is defined as a pseudo-tensor quantity, proportional to the external electromagnetic field tensor. After expanding the eigenvalues of the polarization operator in powers of $k^2$, we obtain approximate dispersion equations (cubic in $k^2$), and analytic solutions for the photon magnetic moment, valid for low momentum and/or large magnetic field. The paramagnetic photon experiences a red shift, with opposite sign than the gravitational one, which differs for parallel and perpendicular polarizations. It is due to the drain of photon transverse momentum and energy by the external field. By defining an effective transverse momentum, the constancy of the speed of light orthogonal to the field is guaranteed. We conclude that the propagation of the photon non-parallel to the magnetic behaves as if there is a quantum compression of vacuum or warp of space-time in an amount depending on its angle with regard to the field.

hep-ph↗

arXiv2013

Quantized Faraday effect in (3+1)-dimensional and (2+1)-dimensional systems

We study Faraday rotation in the quantum relativistic limit. Starting from the photon self-energy in the presence of a constant magnetic field the rotation of the polarization vector of a plane electromagnetic wave which travel along the fermion-antifermion gas is studied. The connection between Faraday Effect and Quantum Hall Effect (QHE) is discussed. The Faraday Effect is also investigated for a massless relativistic (2D+1)-dimensional fermion system which is derived by using the compactification along the dimension parallel to the magnetic field. The Faraday angle shows a quantized behavior as Hall conductivity in two and three dimensions.

hep-ph↗

arXiv2011

2D massless QED Hall half-integer conductivity and graphene

Starting from the photon self-energy tensor in a magnetized medium, the 3D complete antisymmetric form of the conductivity tensor is found in the static limit of a fermion system $C$ non-invariant under fermion-antifermion exchange. The massless relativistic 2D fermion limit in QED is derived by using the compactification along the dimension parallel to the magnetic field. In the static limit and at zero temperature the main features of quantum Hall effect (QHE) are obtained: the half-integer QHE and the minimum value proportional to $e^2/h$ for the Hall conductivity . For typical values of graphene the plateaus of the Hall conductivity are also reproduced.

cond-mat.mes-hall↗

arXiv2010

The photon magnetic moment has not a perpendicular component and is fully paramagnetic

Our paper Phys. Rev. D \textbf{79}, 093002 (2009), in which it was shown the paramagnetic behavior of photons propagating in magnetized vacuum, is criticized in Phys. Rev. D \textbf{81}, 105019, (2010) and even claimed that the photon has a diamagnetic component. Here it is shown that such criticism is inadequate and that the alleged "perpendicular component" is due to a mistake in differentiating a vanishing term with regard to the magnetic field $B$, or either by mistaking the derivative of a scalar product as that of a dyadic product. A discussion on the physical side of the problem is also made.

hep-ph↗

arXiv2010

Photon Redshift in a Magnetic field

Previous results from the authors concerning the arising a tiny photon anomalous paramagnetic moment are also interpreted as a red-shift in analogy to the gravitational known effect. It is due to the photon interaction with the magnetized virtual electron-positron background which withdraw transverse momentum from photons and is polarization-dependent. If the photon frequency red-shift implies a change in time, a clock would go faster for increasing magnetic field intensity.

hep-ph↗

arXiv2010

The paramagnetic photon. Absence of perpendicular component and decay in large fields

Previous results from the authors concerning the arising a tiny photon anomalous paramagnetic moment $μ_γ$ due to its interaction with a magnetized virtual electron-positron background are complemented and discussed. It is argued that such magnetic moment it cannot be a linear function of the angular momentum and that there is no room for the existence of an hypothetical perpendicular component, as recently claimed in the literature. It is discussed that in the region beyond the first threshold, where photons may decay in electron-positron pairs, the photon magnetic moment cannot be defined independently of the magnetic moment of the created pairs. It is shown that for magnetic fields large enough, the vacuum becomes unstable and decays also in electron-positron pairs.

hep-ph↗

arXiv2009

Is the photon paramagnetic?

A photon exhibits a tiny anomalous magnetic moment $μ_γ$ due to its interaction with an external constant magnetic field in vacuum through the virtual electron-positron background. It is paramagnetic ($μ_γ>0$) in the whole region of transparency, i.e. below the first threshold energy for pair creation and has a maximum near this threshold. The photon magnetic moment is different for eigenmodes polarized along and perpendicular to the magnetic field. Explicit expressions are given for $μ_γ$ for the cases of photon energies smaller and closer to the first pair creation threshold. The region beyond the first threshold is briefly discussed.

hep-ph↗

arXiv2008

Series expansion of the photon self-energy in QED and the photon anomalous magnetic moment

We start from the analytical expression of the eigenvalues $κ^{(i)}$ of the photon self-energy tensor in an external constant magnetic field $B$ calculated by Batalin Shabad in the Furry representation, and in the one-loop approximation. We expand in power series of the external field and in terms of the squared photon transverse momentum $z_2$ and (minus) transverse energy $z_1=k^2-z_2$, in terms of which are expressed $κ^{(i)}$. A general expression is given for the photon anomalous magnetic moment $μ_γ>0$ in the region of transparency, below the first threshold for pair creation, and it is shown that it is positive, i.e. paramagnetic. The results of the numerical calculation for $μ_γ>0$ are displayed in a region close to the threshold.

hep-ph↗

arXiv2008

Polarization rotation for light propagating non-parallel to a magnetic field in QED vacuum and in a dilute electron gas

The rotation of the polarization vector for light propagating perpendicular to an external constant external magnetic field $B$, is calculated in quantum vacuum, where it leads to different photon eigenmodes of the magnetized photon self-energy tensor for polarizations along and orthogonal to $B$ (Cotton-Mouton effect in QED vacuum). Its analogies and differences with Faraday effect are discussed and both phenomena are calculated for a relativistic electron gas at low densities, by starting from the low energy limit of the photon self-energy eigenvalues in presence of $B$. In the Cotton-Mouton case the polarization vector describes an ellipse whose axes vary periodically from zero to a maximum value. By assuming an effective electron density of order $10^3$ cm$^{-3}$ the quantum relativistic eigenvalues lead to a rotation of the polarization plane compatible with some of the limit values reported by PVLAS experiments. Other consequences, which are interesting for astrophysics, are also discussed.

hep-ph↗

arXiv2006

Magnetic Fields in Quantum Degenerate Systems and in Vacuum

We consider self-magnetization of charged and neutral vector bosons bearing a magnetic moment in a gas and in vacuum. For charged vector bosons (W bosons) a divergence of the magnetization in both the medium and the electroweak vacuum occurs for the critical field B=B_{wc}=m_{w}^{2}/e. For B>B_{wc} the system is unstable. This behavior suggests the occurrence of a phase transition at B=B_{c}, where the field is self-consistently maintained. This mechanism actually prevents $B$ from reaching the critical value B_{c}. For virtual neutral vector bosons bearing an anomalous magnetic moment, the ground state has a similar behavior for B=B_{nbc}=m_{nb}^{2}/q . The magnetization in the medium is associated to a Bose-Einstein condensate and we conjecture a similar condensate occurs also in the case of vacuum. The model is applied to virtual electron-positron pairs bosonization in a magnetic field B \sim B_{pc}\lesssim 2m_{e}^{2}/e, where m_e is the electron mass. This would lead also to vacuum self-magnetization in QED, where in both cases the symmetry breaking is due to a condensate of quasi-massless particles.

hep-ph↗

arXiv2006

Negative Pressures in QED Vacuum in an External Magnetic Field

Our aim is to study the electron-positron vacuum pressures in presence of a strong magnetic field $B$. To that end, we obtain a general energy-momentum tensor, depending on external parameters, which in the zero temperature and zero density limit leads to vacuum expressions which are approximation-independent. Anisotropic pressures arise, and in the tree approximation of the magnetic field case, the pressure along $B$ is positive, whereas perpendicular to $B$ it is negative. Due to the common axial symmetry, the formal analogy with the Casimir effect is discussed, for which in addition to the usual negative pressure perpendicular to the plates, there is a positive pressure along the plates. The formal correspondence between the Casimir and black body energy-momentum tensors is analyzed. The fermion hot vacuum behavior in a magnetic field is also briefly discussed.

hep-ph↗

arXiv2004

Effect of a Magnetic Field on the Electroweak Symmetry

We discuss the effect of a strong magnetic field in the behavior of the symmetry of an electrically neutral electroweak plasma. We analyze the case of a strong field and low temperatures as compared with the W rest energy. If the magnetic field is large enough, it is self-consistently maintained. Charged vector bosons play the most important role, leading only to a decrease of the symmetry breaking parameter, the symmetry restoration not being possible.

hep-ph↗

arXiv2004

Vacuum pressures and energy in a strong magnetic field

We study vacuum in a strong magnetic field. It shows a nonlinear response, as a ferromagnetic medium. Anisotropic pressures arise, and a negative pressure is exerted in the direction perpendicular to the field. The analogy of this effect with the Casimir effect is analyzed. The vacuum transverse pressure is found to be of the same order of the statistical pressure for $B\sim10^{15}G$ and $N\sim10^{33}electrons/cm^{3}$. Vacuum interaction with the field is studied also for $B\sim10^{16}G$ and larger, including the electron anomalous magnetic moment. We estimate quark contribution to vacuum behavior.

hep-ph↗

arXiv2004

Negative Pressures and Energies in Magnetized and Casimir Vacua

We study the electron-positron vacuum in a strong magnetic field $B$ in parallel with Casimir effect. Use is made of the energy-momentum tensor, taken as the zero temperature and zero density limit of the relativistic quantum statistical tensor. In both magnetic field and Casimir cases it is shown the arising of anisotropic pressures. In the first case the pressure transversal to the field $B$ is negative, whereas along $B$ an usual positive pressure arises. Similarly, in addition to the usual negative Casimir pressure perpendicular to the plates, the existence of a positive pressure along the plates is predicted. The anisotropic pressures suggests a flow of the virtual particles in both cases. By assuming regions of the universe having random orientation of the lines of force, cosmological consequences are discussed in the magnetic field case.

hep-ph↗