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

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.