Towards a Unified Model of Neutrino-Nucleus Reactions for Neutrino Oscillation Experiments

TL;DR

This paper reviews recent progress towards a unified theoretical model of neutrino-nucleus reactions across a wide energy spectrum, crucial for interpreting neutrino oscillation experiments and understanding fundamental neutrino properties.

Contribution

It presents a comprehensive approach combining various reaction mechanisms and models to describe neutrino-nucleus interactions over all relevant energies, advancing the field towards a unified theoretical framework.

Findings

Development of a common cross section formulation for all energy regions

Implementation of a dynamical coupled-channels model for meson production

Application of nuclear spectral functions and Δ-hole models to neutrino-nucleus reactions

Abstract

A precise description of neutrino-nucleus reactions will play a key role in addressing fundamental questions such as the leptonic CP violation and the neutrino mass hierarchy through analyzing data from next-generation neutrino oscillation experiments. The neutrino energy relevant to the neutrino-nucleus reactions spans a broad range and, accordingly, the dominant reaction mechanism varies across the energy region from quasi-elastic scattering through nucleon resonance excitations to deep inelastic scattering. This corresponds to transitions of the effective degree of freedom for theoretical description from nucleons through meson-baryon to quarks. The main purpose of this review is to report our recent efforts towards a unified description of the neutrino-nucleus reactions over the wide energy range; recent overall progress in the field is also sketched. Starting with an overview of the current status of neutrino-nucleus scattering experiments, we formulate the cross section to be commonly used for the reactions over all the energy regions. A description of the neutrino-nucleon reactions follows and, in particular, a dynamical coupled-channels model for meson productions in and beyond the $\Delta$(1232) region is discussed in detail. We then discuss the neutrino-nucleus reactions, putting emphasis on our theoretical approaches. We start the discussion with electroweak processes in few-nucleon systems studied with the correlated Gaussian method. Then we describe quasi-elastic scattering with nuclear spectral functions, and meson productions with a $\Delta$-hole model. Nuclear modifications of the parton distribution functions determined through a global analysis are also discussed. Finally, we discuss issues to be addressed for future developments.