Reducing Flux Uncertainties of NuMI Beamline

The NuMI Off-Axis \(\nu _{e}\) Appearance (NOvA) is a long-baseline accelerator-based neutrino oscillation experiment designed to study the oscillation of muon neutrinos to electron neutrinos ( \(\nu _{\mu } \rightarrow \nu _{e}\) ) using a muon neutrino beam. The long-baseline neutrino oscillation experiments are entering an unprecedented level of precision measurements. Flux is an important input for neutrino oscillation as well as cross-section measurements. Therefore, precise flux prediction is essential to achieve the physics goals of the current and future long-baseline neutrino-oscillation experiments. The typical neutrino flux uncertainty in the current generation of accelerator-based neutrino experiments is between 10% and 15%. To improve the prediction of the neutrino flux, we plan to make corrections based on constraints from the external Hadron Production (HP) experiments like NA61 and EMPHATIC. We will use the Package to Predict Flux (PPFX) to achieve the aforementioned target. In this proceeding, we discuss the GEANT4-based simulation using two different physics lists, FTFP_BERT and QGSP_BERT. We use a tool G4HP to extract cross sections from thin target simulation. The data/MC comparison study of the G4HP simulation with the NA61 hadron production data is shown.