LAUSR

The usage of Monte Carlo neutrino event generators ($\mathrm{MC}\ensuremath{\nu}\mathrm{EG}\mathrm{s}$) is a norm within the high-energy $\ensuremath{\nu}$ scattering community. The relevance of quasielastic (QE) energy regimes to $\ensuremath{\nu}$ oscillation experiments implies that accurate calculations of $\ensuremath{\nu}A$ cross sections in this regime will be a key contributor to reducing the systematic uncertainties affecting the extraction of oscillation parameters. In spite of this, many $\mathrm{MC}\ensuremath{\nu}\mathrm{EG}\mathrm{s}$ utilize highly phenomenological, parametrized models of QE scattering cross sections. Moreover, a culture of validation of $\mathrm{MC}\ensuremath{\nu}\mathrm{EG}$s against prolific electron ($e$) scattering data has been historically lacking. In this work, we implement new $eA$ cross sections obtained from nuclear ab initio approaches in GENIE, the primary $\mathrm{MC}\ensuremath{\nu}\mathrm{EG}$ utilized by the FNAL community. In particular, we utilize results from quantum MC methods which solve the many-body nuclear problem in the short-time approximation (STA), allowing consistent retention of two-nucleon dynamics which are crucial to explain available nuclear electromagnetic (electroweak) data over a wide range of energy and momentum transfers. This new implementation in GENIE is fully tested against the world QE electromagnetic data, finding agreement with available data below $\ensuremath{\sim}2\text{ }\text{ }\mathrm{GeV}$ of beam energy with the aid of a scaling function formalism. The STA is currently limited to study $A\ensuremath{\le}12$ nuclei, however, its semi-inclusive multibody identity components are exportable to other many-body computational techniques such as auxiliary field diffusion MC which can reach $A\ensuremath{\le}40$ systems while continuing to realize the factorization contained within the STA's multinucleon dynamics. Together, these developments promise to make future experiments such as DUNE more accurate in their assessment of $\mathrm{MC}\ensuremath{\nu}\mathrm{EG}$ systematics, $\ensuremath{\nu}$ properties, and potentially empower the discovery of physics beyond the Standard Model.