Effects of Nucleon and Nuclear Structure in Neutrino Interactions

As the precision of neutrino experiments is steadily improving, new data is beginning to highlight problems with current models of neutrino interactions. There exist several unresolved tensions within the global neutrino scattering dataset, and faced with these problems, experiments are forced to turn to data-driven models with errors that can span the spread in experimental observations. The NUISANCE software package was developed to provide a flexible framework for the community to use in the building of these models. This thesis focuses on the extraction of empirical model corrections, to account for several observed tensions in the global scattering dataset, that could have an impact on the T2K oscillation analysis.

Charged current neutrino interaction measurements from MiniBooNE are used to study systematic shifts when tuning the NEUT event generator under different sterile neutrino mixing hypotheses. The results are used to derive an error rescaling method for use in future T2K short baseline oscillation fits.
Alternative models for the quasi-elastic axial form factor are developed, and implemented into NEUT. Data from neutrino-deuterium scattering is used to test each model’s implementation, and extract systematic uncertainties for input to the T2K long baseline oscillation analysis. In addition, NEUT predictions are compared to CC-inclusive data from the MINERvA experiment, highlighting a clear deficiency in its CC0π model. An empirical correction to both the quasi-elastic and multi-nucleon contributions is developed to account for this.

Exclusive data from MINERvA is also used to test the GENIE event generator’s pion production model. The standard GENIE dials are found to provide insufficient coverage of the chosen datasets, and clear tensions are found between these results and earlier tunings to deuterium scattering data. An ad-hoc model correction is developed to account for disagreements in the muon scattering angle distributions, reducing the tensions in the joint fits.