Neutrino Oscillations and Lorentz Violation

Most data acquired to date by experiments in particle physics are successfully described by the minimal Standard Model (SM). One exception is the observation of neutrino oscillations, which are now well established and provide a compelling indication that the minimal SM requires modification. The inclusion of small masses in the neutrino sector of the SM suffices to describe the bulk of the experimental results, although a definitive understanding awaits the results of ongoing and future measurements. From a theoretical perspective, these modifications to the SM could arise as suppressed low-energy energy effects from an underlying unified theory at the Planck scale, mP ≃ 10 GeV. This suggests the interesting possibility that neutrino oscillations might represent signals from the Planck scale. This talk considers the description of neutrino oscillations in terms of a promising candidate Planck-scale signal, namely, violations of relativity arising through Lorentz and CPT breaking. The focus is on neutrino behavior from the perspective of Lorentz and CPT violation in effective quantum field theory. The general effective field theory describing Lorentz and CPT violation is called the Standard-Model Extension (SME) and was the basis for the original suggestion that Lorentz and CPT violation might occur in neutrinos. In the intervening years, several theoretical investigations of this possibility within the context of the SME have been performed, mostly for special models involving only a few coefficients for Lorentz and CPT violation. Here, a comprehensive theoretical study of Lorentz and CPT violation in neutrinos is outlined and a poten-