Decoding Neutrino Interactions: A Model-Independent Approach with DUNE-PRISM

The observed excess of matter over antimatter cannot be explained by Standard Model Charge-Parity (CP) violation alone, motivating searches for additional CP-violating sources in the neutrino sector. The Deep Underground Neutrino Experiment (DUNE) aims to probe leptonic CP violation through precision long-baseline oscillation measurements sensitive to δ . However, its sensitivity depends on disentangling flux and cross-section effects at the 𝐶𝑃 near detector, where event rates constrain only the product ϕ(𝐸 rather than either ν )σ(𝐸 ν ) quantity separately.

This thesis investigates whether DUNE-PRISM off-axis flux matching can partially lift this degeneracy and enable robust measurements of neutrino cross-section single and double ratios. An end-to-end analysis framework was developed, extending idealised flux matching to a measurement-level treatment of event-rate construction, wrong-sign background subtraction, detector response, reconstructed-energy observables, and statistical, flux, and cross-section uncertainty propagation.

The results show that the double ratio reduces systematic uncertainties relative to single ratios, demonstrating enhanced cancellation of correlated effects between species and beam modes. The measurement is systematics-limited rather than statistics-limited: flux systematics provide the dominant contribution, while cross-section uncertainties remain smaller but non-negligible. Wrong-sign beam components modify the uncertainty budget, showing that right-sign-only studies do not capture the behaviour and limitations of the realistic measurement.

Together, these findings demonstrate the feasibility of PRISM-based double-ratio extraction under realistic conditions and identify flux systematic uncertainties as the dominant limitation once the full right-sign and wrong-sign beam composition is considered. The framework developed here supports future DUNE-PRISM cross-section and systematic studies, establishing double-ratio observables as a promising strategy for reducing interaction-model dependence