Spectral function approach in NuWro: modeling of multinucleon final states in quasielastic scattering

TL;DR

This paper enhances the NuWro Monte Carlo generator by implementing a spectral function approach to better model multinucleon final states in quasielastic neutrino scattering, improving agreement with experimental data.

Contribution

The paper introduces an updated spectral function implementation in NuWro that accurately models multinucleon final states in neutrino quasielastic scattering, validated against electron and neutrino data.

Findings

Improved fit to MicroBooNE neutrino data with multinucleon contributions

Reduced chi-squared values from 2.7-7.2 to 1.3-1.8 when including multinucleon effects

Validated spectral function approach against inclusive electron-scattering data.

Abstract

Neutrino-oscillation experiments performed in the few-GeV energy region create an urgent demand for a significant improvement in the accuracy of modeling of neutrino interactions with atomic nuclei. Here, we report an updated implementation of the spectral function approach in the \nuwro{} Monte Carlo generator, which consistently treats multinucleon final-states in quasielastic scattering at the inclusive and exclusive level. After validating its accuracy against inclusive electron-scattering data, we compare its predictions to various neutrino cross sections from MicroBooNE. We find that with the multinucleon contribution, these data are reproduced with $\chi^2$ per degree of freedom of 1.3--1.8, compared to 2.7--7.2 without it.