During this reporting period, significant progress has been made in advancing our understanding of the neutrino interaction with the nuclei. The focus has been on achieving key milestones in the various working packages: Electron scattering data, neutrino scattering data, and Model improvements. Preliminary work has started on the fourth working package: Model tuning. This section details the research findings, technological innovations, and overall progress toward the project's goals.
Electron scattering: A local team of a postdoc, two graduate students and two summer students have made significant progress and their work is nearing publication. Measurements from the CLAS and CLAS12 experiments are already presented in leading conferences: A new inclusive analysis of electron scattering on carbon and argon shows for the first time how problematic the current approach of scaling predictions by the atomic number is. Three semi-exclusive analyses are in the pipe-line: The first being electron scattering with 1 proton and 1 pion is in final stages shading light on the resonance interaction process. The DUNE experiment is the first accelerator-based neutrino oscillation experiment to feature the highest-energy incoming neutrino flux with a broad energy distribution. Given these conditions, numerous neutrino interactions are expected to occur through the resonance process, leading to this specific final state. As a result, this analysis will be crucial for the success of DUNE. Another analysis with only 1 pion in the final state will be of great impact to Cherenkov-based neutirno experiments. A first of a kind analysis of electron scattering with two nucleons (either 2 protons or 1 proton and 1 neutron) is also in progressed stages. The analyser of the last spent a 6 weeks at Jefferson Lab where the experiment is located and worked with local experts to improve the efficiency of neutron detection, crucial for his and others’ analyses.
Neutrino scattering: As part of the MicroBooNE collaboration, we have focused on the neutrino scattering resulting with 1 muon and 1 proton in the final state. Our group member has improved the efficiency to identify relevant vertices. Based on our previous publication, we have suggested and now executing an innovating approach for an oscillation measurement. We choose events with high probability of being quasi elastic as the model of this process is familiar and its uncertainty is low and trustable. Though reducing the number of events increases the statistical uncertainties, the sensitivity is expected to increase as the cross section uncertainties are smaller.
We have had a great progress in the mu4nu initiative, aiming to trigger on muon interaction inside neutirno experiment by identifying multiple prong topologies. In addition our group took a leading part in a pioneering analysis, aiming to use future neutrino scattering data in an innovative way: A measurements of neutrino interactions at different off-axis angles using the DUNE-PRISM detector can be exploited to create narrow virtual fluxes (less than 100 MeV wide).
Models: As planned , our group has made a significant contributions to the electron mode of event generator:
In order to compare data and generated events, radiative effects need to be included in the event generators. We implemented a universal radiative corrections program that can be used with all reaction mechanisms and any eA event generator. This achievement has been recently published.
The second contribution deals with in the Super-Scaling Approach (SuSA) in the GENIE event generator. This approach estimates the inclusive cross section by scaling inclusive electron scattering data on specific nuclei. SuSA’s implementation in the electron mode of GENIE was found to have a problem, simulating only 1n1p events out of the 2p2h finale states (namely, no 2n nor 2p events were generated). A team member has identified and fixed this problem. This fix is now public in the new version of GENIE.
