Neutrino Beam Constraints on Flavor-Diagonal Lorentz Violation

TL;DR

This paper explores how Lorentz violation could cause direction-dependent changes in pion decay, affecting neutrino beam intensity and enabling constraints on Lorentz violation coefficients through sidereal variation analysis.

Contribution

It demonstrates that existing MINOS data can be used to set bounds on flavor-diagonal Lorentz violation affecting muon neutrino speeds.

Findings

Constraints on Lorentz violation coefficients at the 10^(-5) level.

Sidereal variation analysis as a tool for testing Lorentz invariance.

Neutrino beam intensity depends on beam orientation due to Lorentz-violating effects.

Abstract

Breaking of isotropy and Lorentz boost invariance in the dynamics of second-generation leptons would lead to direction-dependent changes in the lifetimes of charged pions. This would make the intensity of a neutrino beam produced via pion decay a function of the beam orientation. The experimental signature of this phenomenon--sidereal variations in the event rate at a downstream neutrino detector--has already been studied, in searches for Lorentz-violating neutrino oscillations. Existing analyses of MINOS near detector data can be used to constrain the flavor-diagonal Lorentz violation coefficients affecting muon neutrino speeds at roughly the 10^(-5) level.