Violation of Lorentz invariance (VLI) has been suggested as an explanation of the superluminal velocities of muon neutrinos reported by OPERA. In this Letter, we show that the amount of VLI required to explain this result poses severe difficulties with the kinematics of the pion decay, extending its lifetime and reducing the momentum carried away by the neutrinos. We show that the OPERA experiment limits alpha = (upsilon(v) - c)/c < 4 x 10(-6). We then take recourse to cosmic-ray data on the spectrum of muons and neutrinos generated in Earth's atmosphere to provide a stronger bound on VLI: (upsilon - c)/c < 10(-12).
Cowsik, Ramanath, Shmuel Nussinov, and Utpal Sarkar. "Superluminal neutrinos at OPERA confront pion decay kinematics." Physical review letters 107.25 (2011): 251801. doi: 10.1103/PhysRevLett.107.251801
American Physical Society