Complementarity Between DUNE and T2HK: Gateway to Improved CP Coverage

We focus on the complementarity between the two upcoming long-baseline experiments: DUNE and T2HK, in establishing the leptonic CP violation at \(\ge 3\sigma \) C.L. for atleast 75% of Dirac CP phase ( \(\delta _{\textrm{CP}}\) ). We explore the crucial role of disappearance mode in establishing the CP violation. We also incorporate the effect of having a probable second detector in Korea (T2HKK). We find that, both DUNE + T2HK is essential for achieving 75% CP coverage, irrespective of \(\sin ^{2}\theta _{23}\) .