Torsion nonminimally coupled to the electromagnetic field and birefringence

Rubilar, Guillermo F.; Obukhov, Yuri N.; Hehl, Friedrich W.

doi:10.1088/0264-9381/20/14/101

Cited by 25 publications

(29 citation statements)

References 14 publications

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“…Calculate the second adjoint matrix for the axion expression (11). It is expressed as a sum of three terms…”

mentioning

confidence: 99%

Photon propagator for axion electrodynamics

Itin

2007

Phys. Rev. D

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The axion modified electrodynamics is usually used as a model for description of possible violation of Lorentz invariance in field theory. The low-energy manifestation of Lorentz violation can hopefully be observed in experiments with the electromagnetic waves. It justifies the importance of study how a small axion addition can modify the wave propagation. Although a constant axion does not contribute to the dispersion relation at all, even a slowly varying axion field destroys the light cone structure. In this paper, we study the wave propagation in the axion modified electrodynamics in the framework of premetric approach. In an addition to the modified dispersion relation, we derive the axion generalization of the photon propagator in Feynman and Landau gauge. Our consideration is free from the usual restriction of a usual restriction to the constant gradient axion field. It is remarkable that the axion modified propagator is hermitian. Consequently the dissipation effects absent even in the phenomenological model considered here. The axion itself can be considered as a fundamental field. Recently some signals on the axion field observations in PVLAS experiments was reported [9]. The new observations, however, do not show the presence of a rotation and ellipticity signals and thus stand a strong upper limit on axion contributions to an optical rotation generated in vacuum by a magnetic field [9].Alternatively, the axion can be viewed as an effective field constructed, for instance, from torsion [10], [11], [12], [13]. Astrophysics consequences of such torsion induced axion models are recently studied intensively, see [14], [15]. Moreover, the linear magnetoelectric effects of Cr 2 O 3 find a satisfactory explanation in term of a macroscopic axion field, see [16]. Some mechanisms that actually lead to axion-type modifications of electrodynamics were proposed recently in [17] and in [18].The axion modified electrodynamics is usually formulated by adding a topological Chern-Simons term to the Maxwell Lagrangian [1], [2], [3]. We apply here an alternative premetric approach to classical electrodynamics [19], [20], [21]. In this construction, the axion field emerges in a natural way as an irreducible part of a general constitutive tensor. In the premetric formalism, one starts with two independent antisymmetric fields: the electromagnetic strength F ij and the excitation field H ij . Here the Roman indices range from 0 to 3. The Maxwell equations are given bywhere the commas denote the ordinary partial derivatives, ǫ ijkl is the Levi-Civita permutation tensor normalized with ǫ 0123 = −ǫ 0123 = 1. The fields F ij and H ij are not independent one on another. For a wide range of physical effect, they can be assumed to be related by a linear homogeneous constitutive lawBy definition, the constitutive pseudotensor is antisymmetric in two pairs of indices. Hence it has, in general, 36 independent components. Its irreducible decomposition under the group of linear transformations involves three independent pieces. One of ...

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“…Calculate the second adjoint matrix for the axion expression (11). It is expressed as a sum of three terms…”

mentioning

confidence: 99%

Photon propagator for axion electrodynamics

Itin

2007

Phys. Rev. D

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“…It is interesting to see that (35) shows a remarkable similarity to the phase shift formula from Moffat's old version of NGT [22]. Nevertheless, while this nonvanishing birefringence was found on the basis of the special BaecklerLee solution, it is important to note that Rubilar et al [19] proved that our nonminimal Lagrangian (1) leads to birefringence even for a general O(3)-symmetric torsion field.…”

Section: Birefringence Analysismentioning

confidence: 59%

Gravity-induced birefringence within the framework of Poincaré gauge theory

et al. 2005

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Gauge theories of gravity provide an elegant and promising extension of general relativity. In this paper we show that the Poincaré gauge theory exhibits gravity-induced birefringence under the assumption of a specific gauge invariant nonminimal coupling between torsion and Maxwell's field. Furthermore we give for the first time an explicit expression for the induced phaseshift between two orthogonal polarization modes within the Poincaré framework. Since such a phaseshift can lead to a depolarization of light emitted from an extended source this effect is, in principle, observable. We use white dwarf polarimetric data to constrain the essential coupling constant responsible for this effect.

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“…Even if spacetime carried torsion and/or nonmetricity, see 4 The Lenz rule and the reason for the relative sign difference between the time derivatives in (7) 2 and (10) 1 are discussed in [22]. [ 21,47,48,52,56], there would be no need to reformulate Maxwell's equations. Therefore…”

Section: Premetric Electrodynamicsmentioning

confidence: 99%

Dimensions and units in electrodynamics

Hehl

Obukhov

2005

Gen Relativ Gravit

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We sketch the foundations of classical electrodynamics, in particular the transition that took place when Einstein, in 1915, succeeded to what one may call premetric classical electrodynamics. This framework will be described shortly. An analysis is given of the physical dimensions involved in electrodynamics and subsequently the question of units addressed. It will be pointed out that these results are untouched by the generalization of classical to quantum electrodynamics (QED). We compare critically our results with those of L.B. Okun which he had presented at a recent conference.

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Torsion nonminimally coupled to the electromagnetic field and birefringence

Cited by 25 publications

References 14 publications

Photon propagator for axion electrodynamics

Photon propagator for axion electrodynamics

Gravity-induced birefringence within the framework of Poincaré gauge theory

Dimensions and units in electrodynamics

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