Narrow Results

Violation of Lorentz invariance and CPT symmetry is a predicted phenomenon of Planck-scale physics. Various types of data are analyzed to search for Lorentz violation under the Standard Model Extension (SME) framework, including neutrino oscillation data. MiniBooNE is a short-baseline neutrino oscillation experiment at Fermilab. The measured excesses from MiniBooNE cannot be reconciled within the neutrino Standard Model (νSM); thus it might be a signal of new physics, such as Lorentz violation. We have analyzed the sidereal time-dependence of MiniBooNE data for signals of the possible breakdown of Lorentz invariance in neutrinos. In this brief review, we introduce Lorentz violation, the neutrino sector of the SME and the analysis of short-baseline neutrino oscillation experiments. We then present the results of the search for Lorentz violation in MiniBooNE data. This review is based on the published result.

The most general theory of electrodynamics with linear field equations introduces a new geometry, the area metric, that regulates the propagation of light rays and massive particles instead of the usual Lorentzian metric. In the majority of the experimental situations, the area metric is expected to be a small perturbation around a metric background. In this perturbative case, two interesting results can be achieved. First, the dynamics of the area metric can be found explicitly. Second, the relative quantum theory of electrodynamics can be shown to be renormalizable and can be used to compute various fundamental processes.

I will show that, when one combines the results of quantum electrodynamics with the dynamics of an area-metric perturbation, the anomalous magnetic moment of the electron, the cross sections of Bhabha scattering, and the hyperfine splitting of the hydrogen pick up a dependence on the position. This way, measurements of the position dependence of these quantities provide a new channel to investigate area-metric deviations from a metric spacetime.