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

Abstract

AbstractWe examine the impact of Lorentz Invariance Violation (LIV) in measuring the octant of $$\theta _{23}$$θ23 and CP phases in the context of the Deep Underground Neutrino Experiment (DUNE). We consider the CPT-violating LIV parameters involving $$e - \mu $$e-μ ($$a_{e\mu }$$aeμ) and $$e - \tau $$e-τ ($$a_{e\tau }$$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 $$\delta $$δ and the new dynamical CP phase $$\varphi _{e\mu }$$φeμ/$$\varphi _{e\tau }$$φeτ, giving rise to new degeneracies among ($$\theta _{23}$$θ23, $$\delta $$δ, $$\varphi $$φ). Taking one LIV parameter at-a-time and considering a small value of $$|a_{e\mu }| = |a_{e\tau }| = 5 \times 10^{-24}$$|aeμ|=|aeτ|=5×10-24 GeV, we find that the octant discovery potential of DUNE gets substantially deteriorated for unfavorable combinations of $$\delta $$δ and $$\varphi _{e\mu }$$φeμ/$$\varphi _{e\tau }$$φeτ. The octant of $$\theta _{23}$$θ23 can only be resolved at $$3\sigma $$3σ if the true value of $$\sin ^2\theta _{23} \lesssim 0.42$$sin2θ23≲0.42 or $$ > rsim 0.62$$≳0.62 for any choices of $$\delta $$δ and $$\varphi $$φ. Interestingly, we also observe that when both the LIV parameters $$a_{e\mu }$$aeμ and $$a_{e\tau }$$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 $$\delta $$δ and $$\varphi _{e\mu }$$φeμ/$$\varphi _{e\tau }$$φeτ. The typical $$1\sigma $$1σ uncertainty on $$\delta $$δ is 10–15$$^{\circ }$$∘ and the same on $$\varphi _{e\mu }$$φeμ/$$\varphi _{e\tau }$$φeτ is 25–30$$^{\circ }$$∘ depending on the choices of their true values.