# Neutral-current weak pion production off the nucleon in covariant chiral perturbation theory

## TL;DR

This paper uses covariant baryon chiral perturbation theory with explicit Δ(1232) degrees of freedom to analyze neutral-current single pion production by neutrinos and antineutrinos on nucleons, revealing significant non-resonant contributions at low energies.

## Contribution

It provides the first detailed relativistic chiral perturbation theory calculation of neutral-current pion production including Δ(1232) effects, highlighting non-resonant contributions often neglected in event generators.

## Key findings

- Non-resonant contributions are sizable at low energies.
- Standard event generators underestimate total cross sections.
- Chiral perturbation theory effectively describes low-energy neutrino-nucleon interactions.

## Abstract

Neutral current single pion production induced by neutrinos and antineutrinos on nucleon targets has been investigated in manifestly relativistic baryon chiral perturbation theory with explicit $\Delta(1232)$ degrees of freedom up to $\mathcal{O}(p^3)$. At low energies, where chiral perturbation theory is applicable, the total cross sections for the different reaction channels exhibit a sizable non-resonant contribution, which is not present in event generators of broad use in neutrino oscillation and cross section experiments such as GENIE and NuWro.