Gauge invariant electromagnetic properties of fermions induced by CPT violation in the Standard Model Extension

Abstract

Low-energy Lorentz-invariant quantities could receive contributions from a fundamental theory producing small Lorentz-violating effects. Within the Lorentz-violating extension of quantum electrodynamics, we investigate, perturbatively, the contributions to the one-loop $ff\gamma$ vertex from the $CPT$-violating axial coupling of a vector background field to fermions. We find that the resulting vertex function has a larger set of Lorentz structures than the one characterizing the usual, Lorentz invariant, parametrization of the $ff\gamma$ vertex. We prove gauge invariance of the resulting one-loop expression through a set of gauge invariant nonrenormalizable operators introducing new-physics effects at the first and second orders in Lorentz violation, and which generate tree-level contributions to the $ff\gamma$ vertex. Whereas loop contributions involving parameters that violate Lorentz invariance at the first order are $CPT$-odd, those arising at the second order are $CPT$-even, so that contributions to low-energy physics are restricted to emerge for the first time at the second order. In this context, we derive a contribution to anomalous magnetic moment of fermions, which we use to set a bound on Lorentz violation.

13 pages, 1 figure, 1 table, a couple of references were added

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Cited by in corpus (20)

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• Topological self-dual configurations in a Lorentz-violating gauged O(3) sigma model
• Generation of geometrical phases and persistent spin currents in 1-dimensional rings by Lorentz-violating terms
• Maxwell electrodynamics modified by CPT-even and Lorentz-violating dimension-6 higher-derivative terms
• General CPT-even dimension-five nonminimal couplings between fermions and photons yielding EDM and MDM
• Maxwell electrodynamics modified by a CPT-odd dimension-five higher-derivative term
• One-loop nonbirefringent effects on the electromagnetic vertex in the Standard Model Extension
• Constraining CPT-odd nonminimal interactions in the Electroweak sector
• External sources in a minimal and nonminimal CPT-odd Lorentz violating Maxwell electrodynamics
• Impact of Lorentz violation on anomalous magnetic moments of charged leptons
• Decays $Z\to \gamma \gamma$ and $Z\to gg$ in the Standard Model Extension
• Self-dual solitons in a $CPT$-odd and Lorentz-violating gauged $O(3)$ sigma model
• Bounds on Lorentz-violating Yukawa couplings via lepton electromagnetic moments
• Electric dipole moments of charged leptons at one loop in the presence of massive neutrinos
• Constraining dimension-six nonminimal Lorentz-violating electron-nucleon interactions with EDM physics
• Effects of universal extra dimensions on top-quark electromagnetic interactions
• Induction of the Lorentz-violating effective actions in quantum electrodynamics
• CPT-Odd effects on the electromagnetic properties of charged leptons in the Standard Model Extension
• Vacuum polarization in Yang-Mills theories with Lorentz violation