GENIE implementation of IFIC Valencia model for QE-like 2p2h neutrino-nucleus cross section

TL;DR

This paper details the implementation of the IFIC Valencia 2p2h neutrino-nucleus cross section model into the GENIE neutrino event generator, including the methodology and limitations of the approach.

Contribution

It introduces a practical implementation of the Valencia 2p2h model in GENIE, enabling simulation of QE-like neutrino interactions with detailed discussion of the physics and limitations.

Findings

Model successfully integrated into GENIE 2.12.6

Provides detailed output and physics context for 2p2h interactions

Framework allows incorporation of other hadronic tensor models

Abstract

The model by Nieves, Ruiz-Simo, and Vicente-Vacas and their group (IFIC, Valencia, Spain) for 2p2h reactions that produce QE-like (no pion) final states has been implemented in GENIE. Since the model currently does not predict the kinematics of the outgoing hadrons, a simple two-nucleon system is grafted onto the model's prediction of isospin, energy transfer, and momentum transfer. These two nucleons are then given to the GENIE FSI models. This technical note is a guide to the kind of information available from this model and some limitations. There are several figures that illustrate the output of the model, and detailed discussion of the physics context for this model. Finally, any other authors' model (or variations of this one) that can be expressed as hadronic tensors for total and pn initial state will be easy to incorporate into this framework, or possibly be made available as a reweight to events generated with this model. The 2017 version of this document is updated to reflect the as-released GENIE 2.12.6 version of the code, which produces identical results to the development versions.