Atmospheric neutrinos analyses in the Deep Underground Neutrino Experiment

Abstract

This thesis explores the physics potential of the Deep Underground Neutrino Experiment (DUNE) with atmospheric neutrinos, focusing on their role in precision oscillation measurements and searches for new physics. A comprehensive procedure was developed for calculating atmospheric event rates, incorporating cross-section models, flux uncertainties, and nuclear effects, with applications to multiple analyses within the collaboration. A key achievement is the first fully simulated and reconstructed atmospheric neutrino study of CP violation in DUNE. While preliminary, this work establishes the foundation for robust oscillation analyses with improved systematics and reconstruction. To address critical uncertainties, we introduced novel treatments of neutrino production height smearing and Earth matter density variations, implementing them for the first time in the MaCh3 Bayesian framework for atmospheric neutrinos. We further validated the performance of the Pandora reconstruction algorithm for atmospheric neutrinos, demonstrating reliable efficiency across energies and topologies. Together, these efforts provide the methodological and computational basis for a comprehensive atmospheric neutrino program in DUNE. Looking ahead, the tools and frameworks developed here will support combined fits with beam and near-detector data, refined flux and cross-section tuning, and enhanced sensitivity to CP violation, mass ordering, and possible physics beyond the Standard Model.