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.Comment: 11 pages, LaTeX file. Minor improvements and new references added. Accepted in Physics Letters

The Lorentz and CPT violating effects on the Z\to l^+ l^- decay

We study the Lorentz and CPT violating effects on the branching ratio BR, the CPT violating asymmetry A_{CPT} and the ratio of the decay width, including only the Lorentz violating effects, to the one obtained in the standard model, for the flavor dependent part of the lepton flavor conserving Z\to l^+ l^- (l=e,\mu,\tau) decay. The inclusion of the Lorentz and CPT violating effects to the standard model contribution is too small to be detected, since the corresponding coefficients are highly suppressed at the low energy scale.Comment: 11 pages, 6 figure

Comments on Lorentz and CPT Violation

This contribution to the CPT'13 meeting briefly introduces Lorentz and CPT violation and outlines two recent developments in the field.Comment: 4 pages, presented at the Sixth Meeting on CPT and Lorentz Symmetry, Bloomington, Indiana, June 17-21, 201