Neutrino-Nucleus Scattering Cross Sections at Medium Energies

TL;DR

The paper surveys neutrino–nucleus scattering at medium energies, detailing the electroweak formalism, dominant interaction channels (QE, resonances, SIS/DIS), and the array of nuclear effects (binding, Fermi motion, Pauli blocking, MECs, correlations, FSIs) that shape observed cross sections. It outlines a spectrum of modeling approaches—from Fermi gas and scaling theories to mean-field, spectral-function, and ab initio methods—emphasizing their domain of validity and role as benchmarks for modern neutrino event generators. The experimental landscape is mapped from short- to long-baseline programs and dedicated cross‑section experiments, highlighting how precise cross-section data on diverse targets and energies underpin oscillation measurements and flux normalization. The work underscores the essential dialogue between theory and experiment, the incorporation of uncertainty quantification via χEFT and ab initio methods, and the central goal of achieving percent-level precision in oscillation analyses for next-generation facilities like DUNE and Hyper-K. Overall, the chapter provides a detailed, data-driven framework for understanding and predicting neutrino–nucleus interactions across the medium-energy regime, linking fundamental weak interactions to complex nuclear dynamics.

Abstract

The weak interactions of neutrinos with other Standard Model particles are well described within the Standard Model of particle physics. However, modern accelerator-based neutrino experiments employ nuclei as targets, where neutrinos interact with bound nucleons, turning a seemingly simple electroweak process into a complex many-body problem in nuclear physics. At the time of writing this Encyclopedia of Particle Physics chapter, neutrino-nucleus interactions remain one of the leading sources of systematic uncertainty in accelerator-based neutrino oscillation measurements. This chapter provides a pedagogical overview of neutrino interactions with nuclei in the medium-energy regime, spanning a few hundred MeV to several GeV. It introduces the fundamental electroweak formalism, outlines the dominant interaction mechanisms - including quasielastic scattering, resonance production, and deep inelastic scattering - and discusses how nuclear effects such as Fermi motion, nucleon-nucleon correlations, meson-exchange currents, and final-state interactions modify observable cross sections. The chapter also presents a brief survey of the foundational and most widely used theoretical models for neutrino-nucleus cross sections, together with an overview of current and upcoming accelerator-based neutrino oscillation experiments that are shaping the field. Rather than targeting experts, this chapter serves as a primer for advanced undergraduates, graduate students, and early-career researchers entering the field. It provides a concise foundation for understanding neutrino-nucleus scattering, its relevance to oscillation experiments, and its broader connections to both particle and nuclear physics.

Figures (7)

• Figure 1: Illustration of neutrino production mechanisms (left) and the resulting medium-energy neutrino fluxes (right) at accelerator-based experiments.
• Figure 2: (Left) Radial dependence of the nucleon--nucleon potential, illustrating its long-range attraction and short-range repulsion. (Right) Schematic representation of a one-nucleon knockout in a shell-model picture, where the residual nucleus is left in a one-hole state.
• Figure 3: Schematic representation of neutrino–nucleus scattering as a function of energy transfer to the nucleus, highlighting the dominant interaction processes. The top of the schematic illustrates the corresponding evolution of effective degrees of freedom.
• Figure 4: Diagrammatic representation of dominant neutrino–nucleus scattering channels: (a) quasielastic scattering, (b) resonance production, and (c) deep-inelastic scattering.
• Figure 5: A diagrammatic representation of dominant two-body meson–exchange current (MEC) processes in nuclei: (a) seagull (contact) current, (b) pion–in–flight current, and (c) $\Delta$–isobar current contributions.