Lorentz Breaking Terms Research Articles

Aetherlike Lorentz-breaking actions

We demonstrate the generation of the CPT-even, aether-like Lorentz-breaking actions for the scalar and electromagnetic fields via their appropriate Lorentz-breaking coupling to spinor fields in three, four and five space-time dimensions. Besides, we show that the aether-like terms for the spinor field also can be generated as a consequence of the same couplings. Also we discuss the dispersion relations in the theories with aether-like Lorentz-breaking terms and find the tree-level effective (Breit) potential for fermion scattering and the one-loop effective potential corresponding to the action of the scalar field.

Renormalization group in Lifshitz-type theories

We study the one-loop renormalization and evolution of the couplings in scalar field theories of the Lifshitz type, i.e. with different scaling in space and time. These theories are unitary and renormalizable, thanks to higher spatial derivative terms that modify the particle propagator at high energies, but at the expense of explicitly breaking Lorentz symmetry. We study if and under what conditions the Lorentz symmetry can be considered as emergent at low energies by studying the RG evolution of the ``speed of light'' coupling c2 and, for more than one field, of δc2≡c21−c22 in simple models. We find that in the UV both c2 and δc2 generally flow logarithmically with the energy scale. A logarithmic running of c2 persists also at low-energies, if δc2≠0 in the UV. As a result, Lorentz symmetry is not recovered at low energies with the accuracy needed to withstand basic experimental constraints, unless all the Lorentz breaking terms, including δc2, are unnaturally fine-tuned to extremely small values in the UV. We expect that the considerations of this paper will apply to any generic theory of Lifshitz type, including a recently proposed quantum theory of gravity by Hořava.

Dual equivalence between self-dual and Maxwell-Chern-Simons models with Lorentz symmetry breaking

In this paper, we use the gauge embedding procedure and the master action approach to establish the equivalence between the self-dual and the Maxwell-Chern-Simons models with Lorentz symmetry breaking. As a result, new kinds of Lorentz-breaking terms arise.

On the renormalization of CPT/Lorentz violating QED in curved space

We consider the one-loop renormalization of QED in curved space-time with additional Lorentz and/or CPT breaking terms. The renormalization group equations in the vacuum sector are derived. In the special case of Minkowski metric and with constant Lorentz and CPT breaking terms these equations reduce to the ones obtained earlier by other authors. The necessary form of the vacuum counterterms indicate possible violations of the space or time homogeneity or space isotropy in the gravitational phenomena. However, the necessity of the phenomenologically most interesting terms such as linear in the space-time curvature or torsion, is related to the non-constant nature of the dimensionless Lorentz and CPT breaking parameters.

Aspects of causality and unitarity and comments on vortexlike configurations in an Abelian model with a Lorentz-breaking term

The gauge-invariant Chern-Simons-type Lorentz- and CPT-breaking term is here reassessed and a spin-projector method is adopted to account for the breaking (vector) parameter. Issues like causality, unitarity, spontaneous gauge-symmetry breaking and vortex formation are investigated, and consistency conditions on the external vector are identified.