Exclusive $\pi^{-}$ Electroproduction off the Neutron in Deuterium in the Resonance Region

TL;DR

This paper reports new measurements of exclusive $$ electroproduction off neutrons in deuterium, providing valuable data for understanding nucleon resonances and improving models of neutrino-nucleus interactions.

Contribution

It presents the first detailed extraction of neutron cross sections and structure functions in the resonance region over a wide kinematic range, including separation of final-state interactions.

Findings

Kinematic separation of final-state interactions from quasi-free cross sections.

Extraction of structure functions and Legendre moments for neutron electroproduction.

Data will aid in determining $Q^{2}$ evolution of $n o N^{*}$ amplitudes.

Abstract

New results for the exclusive and quasi-free cross sections off neutrons bound in deuterium ${\gamma}_vn(p) \rightarrow p{\pi}^{-} (p)$ are presented over a wide final state hadron angle range with a kinematic coverage of the invariant mass ($W$) up to 1.825 GeV and the virtual photon four-momentum transfer squared ($Q^{2}$) from 0.4 to 1.0 GeV$^2$. The exclusive structure functions were extracted and their Legendre moments were obtained. Final-state-interaction contributions have been kinematically separated from the extracted quasi-free cross sections off bound neutrons solely based on the analysis of the experimental data. These new results will serve as long-awaited input for phenomenological analyses to extract the $Q^{2}$ evolution of previously unavailable $n \to N^{*}$ electroexcitation amplitudes and to improve state-of-the-art models of neutrino scattering off nuclei by augmenting the already available results from free protons.