New Constraints on Neutrino Velocities

TL;DR

This paper refutes the claim that neutrinos travel faster than light by showing they would lose energy through pair production, and uses observational data to set new limits on neutrino superluminality.

Contribution

It provides a theoretical energy loss argument against superluminal neutrinos and establishes new experimental limits using Super-Kamiokande and IceCube data.

Findings

Superluminal neutrinos would rapidly lose energy via pair production.

Most high-energy neutrinos would be depleted en route if superluminal.

New limits on neutrino superluminal velocities are derived from observational data.

Abstract

The OPERA collaboration has claimed that muon neutrinos with mean energy of 17.5 GeV travel 730 km from CERN to the Gran Sasso at a speed exceeding that of light by about 7.5 km/s or 25 ppm. However, we show that such superluminal neutrinos would lose energy rapidly via the bremsstrahlung of electron-positron pairs ($\nu\rightarrow \nu+e^-+e^+$). For the claimed superluminal neutrino velocity and at the stated mean neutrino energy, we find that most of the neutrinos would have suffered several pair emissions en route, causing the beam to be depleted of higher energy neutrinos. Thus we refute the superluminal interpretation of the OPERA result. Furthermore, we appeal to Super-Kamiokande and IceCube data to establish strong new limits on the superluminal propagation of high-energy neutrinos.