Precision in Atmospheric Oscillation Parameters and Octant Resolution of ϑ23 through DUNE's eye

Neutrino oscillation study has entered into the precision era and hence a high precision measurement of ϑ23 mixing angle is pivotal to addressing long-standing flavor problems by ruling out different theoretical mass models. The potential of the upcoming Deep Underground Neutrino Experiment (DUNE) is highly promising to shed light on the precision of atmospheric oscillation parameters. Current global fit analyses of world oscillation data under the 3ν-paradigm give 1.6σ indications for lower ϑ23 octant and prefer normal mass ordering (NMO) at 2.5σ.  In this work, we study in detail the capability of DUNE to resolve ϑ23 octant at a high confidence level in light of present neutrino oscillation data. We observe that DUNE can improve the relative 1σ precision in sin2ϑ23 (Δm231 ) by a factor of 4.4 (2.8) using 3.5 years of neutrino and 3.5 years of antineutrino runs, which improves further for 10 years of run-time. We have further shown that DUNE is more promising in measuring Δm231 with higher precision than the upcoming JUNO experiment and synergies of experiments considered in global-fit studies. We have also shown, octant ambiguity of ϑ23 can be resolved at 3σ (5σ) in DUNE with 336 kt.MW.years exposure if true sin2ϑ23<0.462(0.450) or sin2ϑ23>0.553(0.569) assuming true δCP =223º and true NMO.