Squeezing the Parameter Space for Lorentz Violation in the Neutrino Sector by Additional Decay Channels

TL;DR

This paper explores how additional decay channels like neutrino splitting can tighten constraints on Lorentz violation in the neutrino sector, offering new bounds and insights into symmetry breaking.

Contribution

It introduces the consideration of neutrino splitting as a decay channel to improve bounds on Lorentz violation, extending previous analyses based on neutrino decay probabilities.

Findings

Neutrino splitting provides more stringent bounds on Lorentz violation.

Additional decay channels can significantly tighten constraints.

Discussion of theoretical models linking Lorentz and gauge symmetry breaking.

Abstract

The hypothesis of Lorentz violation in the neutrino sector has intrigued scientists for the last two to three decades. A number of theoretical arguments support the emergence of such violations first and foremost for neutrinos, which constitute the "most elusive" and "least interacting" particles known to mankind. It is of obvious interest to place stringent bounds on the Lorentz-violating parameters in the neutrino sector. In the past, the most stringent bounds have been placed by calculating the probability of neutrino decay into a lepton pair, a process made kinematically feasible by Lorentz violation in the neutrino sector, above a certain threshold. However, even more stringent bounds can be placed on the Lorentz-violating parameters if one takes into account, additionally, the possibility of neutrino splitting, i.e., of neutrino decay into a neutrino of lower energy, accompanied by "neutrino-pair Cerenkov radiation". This process has negligible threshold and can be used to improve the bounds on Lorentz-violating parameters in the neutrino sector. Finally, we take the opportunity to discuss the relation of Lorentz and gauge symmetry breaking, with a special emphasis on the theoretical models employed in our calculations.