Measurement of Coherent Production of $\pi^\pm$ in Neutrino and Anti-Neutrino Beams on Carbon from $E_\nu$ of $1.5$ to $20$ GeV

TL;DR

This paper reports a model-independent measurement of coherent charged pion production by neutrinos and anti-neutrinos on carbon, revealing discrepancies with existing neutrino interaction models used in oscillation experiments.

Contribution

It provides the first direct measurement of the differential cross section for coherent pion production on carbon in the 1.5 to 20 GeV energy range, challenging current theoretical models.

Findings

Poor agreement with predicted kinematics in neutrino generators.

First model-independent measurement of the process.

Highlights need for improved theoretical models.

Abstract

Neutrino-induced coherent charged pion production on nuclei, $\stackrel{(-)}{\nu}_\mu A\to\mu^\pm\pi^\mp A$ is a rare, inelastic interaction in which a small squared four-momentum $| t|$ is transferred to the recoil nucleus leaving it intact in the reaction. In the scintillator tracker of MINERvA, we remove events with evidence of particles from nuclear breakup and reconstruct $| t|$ from the final state pion and muon. We select low $| t|$ events to isolate a sample rich in coherent candidates. By selecting low $| t|$ events we produce a model-independent measurement of the differential cross section for coherent scattering of neutrinos and anti-neutrinos on carbon. We find poor agreement with the predicted kinematics in neutrino generators used by current oscillation experiments.