Probing Lorentz and CPT Violation in a Magnetized Iron Detector using Atmospheric Neutrinos

Abstract

We study the sensitivity of the Iron Calorimeter (ICAL) at the India-Based Neutrino Observatory (INO) to Lorentz and CPT violation in the neutrino sector. Its ability to identify the charge of muons in addition to their direction and energy makes ICAL a useful tool in putting constraints on these fundamental symmetries. Using resolution, efficiencies, errors and uncertainties obtained from ICAL detector simulations, we determine sensitivities to $\delta{b}_{31}$, which parametizes the violations in the muon neutrino sector. We carry out calculations for three generic cases representing mixing in the CPT violating part of the hamiltonian, specifically, when the mixing is 1) small, 2) large, 3) the same as that in the PMNS matrix. We find that for both types of hierarchy, ICAL at INO should be sensitive to $\delta{b}_{31}$ $\gtrsim$ $4\times10^{-23}$ GeV at 99% C.L. for 500 kt-yr exposure, unless the mixing in the CPT violation sector is small.