Consistency of isotropic modified Maxwell theory: Microcausality and unitarity

We have studied a (1+2)-dimensional Lorentz-violating model which is obtained from the dimensional reduction of the nonbirefringent sector of the CPT-even electrodynamics of the standard model extension (SME). The planar theory contains a gauge sector and a scalar sector which are linearly coupled by means of a Lorentz-invariance violating (LIV) vector, S µ , while the kinetic terms of both sectors are affected by the components of a Lorentz-violating symmetric tensor, κ µν . The energy-momentum tensor reveals that both sectors present energy stability for sufficiently small values of the Lorentz-violating parameters. The full dispersion relation equations are exactly determined and analyzed for some special configurations of the LIV backgrounds, showing that the planar model is entirely nonbirefringent at any order in the LIV parameters. At first order, the gauge and scalar sectors are described by the same dispersion relations. Finally, the equations of motion have been solved in the stationary regime and at first order in the LIV parameters. It is observed that the Lorentz-violating parameters do not alter the asymptotical behavior of the electric and magnetic fields but induce an angular dependence which is not present in Maxwell's planar theory.

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“…This CPT-even sector has also been recently investigated in connection with consistency aspects in Refs. [21,22].…”

Section: Introductionmentioning

confidence: 99%

Aspects of a planar nonbirefringent andCPT-even electrodynamics stemming from the standard model extension

2011

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“…The Cherenkov-like emission of a photon by a proton of charge e p ≡ e is then already possible in the vacuum. The modifications introduced by κ to the photon polarization vectorsε (2.2) for the gauge field A µ , with proper normalization factors from the quantum theory [11,13].…”

Section: Vacuum Cherenkov Radiationmentioning

confidence: 99%

“…The quantum theory corresponding to (2.7) has been studied in Ref. [11], in particular as regards microcausality and unitarity.…”

Section: Introductionmentioning

confidence: 99%

Parton-model calculation of a nonstandard decay process in isotropic modified Maxwell theory

Díaz

Klinkhamer

2015

Phys. Rev. D

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We have performed a calculation in the parton-model approximation of a nonstandard decay process in isotropic modified Maxwell theory coupled to standard Dirac theory, with a single Lorentz-violating parameter κ in the photonic sector. Previous calculations of this process (vacuum Cherenkov radiation by a proton for the theory with κ > 0) were performed for pointlike particles, and an upper bound on κ at the 10 −19 level was obtained from experimental data on ultra-high-energy cosmic rays. The parton-model results change the decay rate by about an order of magnitude but give the same upper bound on κ because the threshold energy is unchanged. The previous point-particle calculation of photon decay into an electron-positron pair for the theory with κ < 0 remains valid, and experimental results on cosmic gamma rays provide a lower bound on κ at the −10 −15 level.

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“…[10], the same authors classified the components of the rank-4 tensor (K F ) µναβ into birefringent and nonbirefrintent. Since those works, this CP T -even, but Lorentz-violating, parametrization has been the subject of diverse works in both the theoretical [20,[22][23][24][25][26][27][28][29][30][31][32] and experimental [33][34][35][36] sides. There is a clear difference concerning the experimental sensitivity reached for each set of parameters, for the constraints established for the birefringent coefficients are more stringent than the current bounds restricting the nonbirefringent components by several orders of magnitude.…”

Section: The Nonbirefringent Lorentz-violating Photon Propagatormentioning

confidence: 99%

One-loop nonbirefringent effects on the electromagnetic vertex in the Standard Model Extension

Moyotl

Novales‐Sánchez

Toscano

et al. 2014

Int. J. Mod. Phys. A

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Lorentz violation emerged from a fundamental description of nature may impact, at low energies, the Maxwell sector, so that contributions from such new physics to the electromagnetic vertex would be induced. Particularly, nonbirefringent CP T -even effects from the electromagnetic sector modified by the Lorentz-and CP T -violating Standard Model Extension alter the structure of the free photon propagator. We calculate Lorentz-violating contributions to the electromagnetic vertex, at the one-loop level, by using a modified photon propagator carrying this sort of effects. We take the photon off shell, and find an expression that involves both isotropic and anisotropic effects of nonbirefringent violation of Lorentz invariance. Our analysis of the one-loop vertex function includes gauge invariance, transformation properties under C, P , and T , and tree-level contributions from Lorentz-violating nonrenormalizable interactions. These elements add to previous studies of the one-loop contributions to the electromagnetic vertex in the context of Lorentz violation in the photon sector. Finally, we restrict our analysis to the isotropic case and derive a finite contribution from isotropic Lorentz violation to the anomalous magnetic moment of fermions that coincides with the result already reported in the literature.

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Consistency of isotropic modified Maxwell theory: Microcausality and unitarity

Cited by 111 publications

References 55 publications

Aspects of a planar nonbirefringent andCPT-even electrodynamics stemming from the standard model extension

Aspects of a planar nonbirefringent andCPT-even electrodynamics stemming from the standard model extension

Parton-model calculation of a nonstandard decay process in isotropic modified Maxwell theory

One-loop nonbirefringent effects on the electromagnetic vertex in the Standard Model Extension

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