Heavy Neutral Leptons event selection at the ProtoDUNE experiment for NP04 LArTPC

In this work, we present a sensitivity study for the detection of Heavy Neutral Leptons (HNLs) with the ProtoDUNE-SP (NP04) detector at CERN. ProtoDUNE-SP is a large-scale single-phase Liquid Argon Time Projection Chamber (LArTPC) that utilizes a 400 GeV proton beam from the Super Proton Synchrotron (SPS). HNLs are hypothetical particles, predicted by seesaw extensions of the Standard Model, which could explain neutrino masses and the matter-antimatter asymmetry of the universe. The experiment's high-intensity beamline and large active volume enable it to probe HNL couplings significantly weaker than those accessible to previous experiments such as SHiP and NA62. Using Monte Carlo simulations of signal and background processes, we detail the HNL phenomenology relevant to NP04, analyze neutrino background sources, and perform a cut-based event selection to determine detection efficiencies.