# Search for Lorentz and CPT violation using sidereal time dependence of neutrino flavor transitions over a short baseline

## TL;DR

This study searched for sidereal time variations in neutrino flavor transitions to detect possible Lorentz and CPT violations, finding no evidence but setting the most stringent limits to date on such violations at the GeV scale.

## Contribution

First to derive limits on Lorentz and CPT violation terms from the Standard Model Extension using sidereal modulation data in neutrino experiments.

## Key findings

- No evidence of sidereal modulations was observed.
- Established new upper limits on Lorentz and CPT violating parameters.
- Results suggest such symmetry violations are suppressed by over 10^20 at GeV energies.

## Abstract

A class of extensions of the Standard Model allows Lorentz and CPT violations, which can be identified by the observation of sidereal modulations in the neutrino interaction rate. A search for such modulations was performed using the T2K on-axis near detector. Two complementary methods were used in this study, both of which resulted in no evidence of a signal. Limits on associated Lorentz and CPT violating terms from the Standard Model Extension have been derived taking into account their correlations in this model for the first time. These results imply such symmetry violations are suppressed by a factor of more than $10^{20}$ at the GeV scale.