  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.
