Testing Lorentz and CPT Invariance with MINOS Near Detector Neutrinos

TL;DR

This paper develops methods to detect Lorentz and CPT violations in neutrino data using the MINOS near detector, employing Fourier analysis to identify sidereal variations and establish upper limits on violations.

Contribution

It introduces a novel analysis technique using FFT to search for Lorentz and CPT violations in neutrino experiments within the SME framework.

Findings

Developed methods to identify sidereal variations in neutrino event rates.

Simulated experiments to determine detection thresholds for Lorentz and CPT violations.

Established upper limits on Lorentz and CPT violating parameters.

Abstract

We present an analysis designed to search for Lorentz and CPT violations as predicted by the SME framework using the charged current neutrino events in the MINOS near detector. In particular we develop methods to identify periodic variations in the normalized number of charged current neutrino events as a function of sidereal phase. To test these methods, we simulated a set of 1,000 experiments without Lorentz and CPT violation signals using the standard MINOS Monte Carlo. We performed an FFT on each of the simulated experiments to find the distribution of powers in the sidereal phase diagram without a signal. We then injected a signal of increasing strength into the sidereal neutrino oscillation probability until we found a 5$\sigma$ deviation from the mean in the FFT power spectrum. By this method, we can establish upper limits for the Lorentz and CPT violating terms in the SME.