Implementation of the SuSAv2-meson exchange current 1p1h and 2p2h models in GENIE and analysis of nuclear effects in T2K measurements

S Dolan,G D Megias,S Bolognesi

doi:10.1103/physrevd.101.033003

Abstract

We first present the implementation and validation of the SuSAv2-MEC 1p1h and 2p2h models in the GENIE neutrino-nucleus interaction event generator and a comparison of the subsequent predictions to measurements of lepton and hadron kinematics from the T2K experiment. These predictions are also compared to those of other available models in GENIE. We additionally compare the semi-inclusive predictions of the implemented 1p1h model to those of the microscopic model on which SuSAv2 is based - Relativistic Mean Field (RMF) - to begin to test the validity of widely-used `factorisation' assumptions employed by generators to predict hadron kinematics from inclusive input models. The results highlight that a more precise treatment of hadron kinematics in generators is essential in order to attain the few-% level uncertainty on neutrino interactions necessary for the next generation of accelerator-based long-baseline neutrino oscillation experiments.

Highlights

The modeling of neutrino-nucleus interactions in the one-to-few GeV region is one of the most complicated issues facing current long-baseline neutrino oscillation measurements (T2K, NOνA) and is expected to be one of the limiting factors for the sensitivity of the future experiments such as DUNE and T2HK [1]
The SuSAv2 1p1h and 2p2h models have been implemented in the GENIE event generator and shown to produce results consistent with the inclusive model predictions
The SuSAv2 models have been well validated on electron scattering data, making this the first complete (1p1h þ 2p2h) implementation in GENIE to have been so

Summary

INTRODUCTION

The modeling of neutrino-nucleus interactions in the one-to-few GeV region is one of the most complicated issues facing current long-baseline neutrino oscillation measurements (T2K, NOνA) and is expected to be one of the limiting factors for the sensitivity of the future experiments such as DUNE and T2HK [1]. Recent experimental results focus on multidimensional and/or “semi-inclusive” measurements, where the outgoing lepton and some hadron(s) are detected in coincidence (e.g., lepton and highest momentum proton kinematics in measurements of CC0π interactions), whilst many of the available models are only able to calculate “inclusive” cross sections, which integrate over all possible hadronic final states (i.e., they are able to directly predict outgoing lepton kinematics but can say nothing about outgoing hadrons) [40] For these models, it is only by their implementation in event generators that they can be used to predict the semiinclusive final states. The comparison to crosssection measurements is crucial in order to estimate the systematic uncertainties induced by the usage of such approximated approaches in measurements of neutrino oscillations Throughout this manuscript all GENIE predictions are made using GENIE version R-3_00_02 [41] which serves as the base model for the implementations presented here. The full SuSAv2 implementation is expected to be in the public GENIE release (R-3_02_00) but a preliminary version of the code can be found in [42]

IMPLEMENTATION IN GENIE AND THE FACTORIZATION APPROACH

COMPARISON OF SuSAv2 2P2H WITH OTHER MODELS

COMPARISON OF SUSAV2 IMPLEMENTATION WITH SEMI-INCLUSIVE MEASUREMENTS

Findings

CONCLUSIONS