Can Lorentz invariance violation affect the sensitivity of deep underground neutrino experiment?

Abstract

We examine the impact of Lorentz Invariance Violation (LIV) in measuring the octant of θ23 and CP phases in the context of the Deep Underground Neutrino Experiment (DUNE). We consider the CPT-violating LIV parameters involving e- μ (aeμ) and e- τ (aeτ) flavors, which induce an additional interference term in neutrino and antineutrino appearance probabilities. This new interference term depends on both the standard CP phase δ and the new dynamical CP phase φeμ/φeτ, giving rise to new degeneracies among (θ23, δ, φ). Taking one LIV parameter at-a-time and considering a small value of | aeμ| = | aeτ| = 5 × 10 - 24 GeV, we find that the octant discovery potential of DUNE gets substantially deteriorated for unfavorable combinations of δ and φeμ/φeτ. The octant of θ23 can only be resolved at 3 σ if the true value of sin 2θ23≲ 0.42 or ≳ 0.62 for any choices of δ and φ. Interestingly, we also observe that when both the LIV parameters aeμ and aeτ are present together, they cancel out the impact of each other to a significant extent, allowing DUNE to largely regain its octant resolution capability. We also reconstruct the CP phases δ and φeμ/φeτ. The typical 1 σ uncertainty on δ is 10–15∘ and the same on φeμ/φeτ is 25–30∘ depending on the choices of their true values.