Enhancing the sensitivity to neutrino oscillation parameters using synergy between T2K, NOνA and JUNO
摘要
We study the impact of combining the present NOνA and T2K data with simulated data from the JUNO experiment on the determination of the leptonic CP phase and the neutrino mass hierarchy. The current NOνA data exhibit a hierarchy-δCP degeneracy, admitting both normal hierarchy (NH) with δCP ∈ [0, 180°], and inverted hierarchy (IH) with δCP ∈ [180°, 360°] solutions at comparable significance, while T2K prefers δCP ≃ 270° for both hierarchies, leading to a 2σ tension between the two experiments for normal hierarchy. Using detailed GLoBES simulations, we show that future JUNO data with excellent hierarchy sensitivity, can lift the hierarchy-δCP degeneracy in NOνA and strengthen the hierarchy reach of T2K in spite of having no δCP sensitivity. Allowing the hierarchy to be a free parameter in the fit, if the true ordering is IH, JUNO aligns the NOνA and T2K allowed regions and resolves their present tension; if NH is true, the tension continues to persist. We also show that JUNO’s precise measurement of |∆31| leads to improved constraints on sin2 θ23 and δCP for normal mass hierarchy in NOνA even though JUNO itself is insensitive to these parameters. Finally, updated solar-parameter measurements from JUNO’s first data release further enhance the combined precision. Our results demonstrate that JUNO plays a crucial synergistic role in the global neutrino-oscillation programme, enabling a more robust determination of the mass ordering and improving the sensitivity to the CP phase when combined with long-baseline data.