Superluminal neutrinos in long baseline experiments and SN1987a

TL;DR

This paper examines superluminal neutrino velocities observed in experiments like MINOS and OPERA, explores Lorentz violation models, and discusses tensions with supernova bounds and energy independence of the effect.

Contribution

It introduces a generalized parametrization of Lorentz violation in neutrinos and a toy model explaining energy-dependent effects beyond standard quadratic forms.

Findings

OPERA and MINOS suggest superluminal neutrino velocities

Tension exists between laboratory results and supernova bounds

Energy independence of neutrino velocity anomalies is supported

Abstract

Precise tests of Lorentz invariance in neutrinos can be performed using long baseline experiments such as MINOS and OPERA or neutrinos from astrophysical sources. The MINOS collaboration reported a measurement of the muonic neutrino velocities that hints to super-luminal propagation, very recently confirmed at 6 sigma by OPERA. We consider a general parametrisation which goes beyond the usual linear or quadratic violation considered in quantum-gravitational models. We also propose a toy model showing why Lorentz violation can be specific to the neutrino sector and give rise to a generic energy behaviour E^alpha, where alpha is not necessarily an integer number. Supernova bounds and the preferred MINOS and OPERA regions show a tension, due to the absence of shape distortion in the neutrino bunch in the far detector of MINOS. The energy independence of the effect has also been pointed out by the OPERA results.