Methods for constraining systematic uncertainties for precision neutrino oscillation measurements with the NOvA Experiment

The NOvA collaboration studies neutrino oscillations using an 810 km long baseline ranging from the neutrino source, the megawatt-capable NuMI beam at Fermilab, to the far detector target in Minnesota. With 10 years of data, NOvA uses a technique called "extrapolation" to mitigate systematic uncertainties. Simulation-data discrepancies in unoscillated spectra at the near detector are propagated as corrections to the far detector simulation. The oscillation measurement is then performed at the far detector by comparing the extrapolation-corrected simulation and the observed NuMI spectra. In addition to extrapolation, NOvA is exploring a joint two-detector fitting method. With two-detector fitting, systematic uncertainties would be constrained simultaneously at both the near and far detector, with the oscillation parameter measurement at the far detector. This would be an important check of the robustness of the extrapolation method, and since NOvA is systematic-limited in some neutrino mixing parameter measurements, a tighter constraint on the systematics could yield a stronger constraints on oscillation models. In this talk, I will discuss the differences between these approaches and the of future oscillation fitting in NOvA.