Neutral Pion Electroproduction in the Resonance Region at High $Q^2$

TL;DR

This paper reports measurements of neutral pion electroproduction at high momentum transfer, providing insights into the electromagnetic properties of the Δ(1232) resonance and extending understanding of resonance behavior at high $Q^2$.

Contribution

It presents new high-$Q^2$ differential cross section data for $ep o e' p' \pi^0$ in the resonance region, with detailed analysis of resonance electromagnetic properties.

Findings

The $ ext{Δ}(1232)$ resonance contribution continues to decline rapidly at high $Q^2$.

Data on electromagnetic ratios $R_{EM}$ and $R_{SM}$ are provided at unprecedented $Q^2$ values.

The magnetic transition form factor $G_M^{ ext{*}}$ shows a specific $Q^2$ dependence.

Abstract

The process $ep \to e^{\prime}p^{\prime}\pi^0$ has been measured at $Q^2$ = 6.4 and 7.7 GeV/c$^2$)$^2$ in Jefferson Lab's Hall C. Unpolarized differential cross sections are reported in the virtual photon-proton center of mass frame considering the process $\gamma^{\ast}p \to p^{\prime}\pi^0$. Various details relating to the background subtractions, radiative corrections and systematic errors are discussed. The usefulness of the data with regard to the measurement of the electromagnetic properties of the well known $\Delta(1232)$ resonance is covered in detail. Specifically considered are the electromagnetic and scalar-magnetic ratios $R_{EM}$ and $R_{SM}$ along with the magnetic transition form factor $G_M^{\ast}$. It is found that the rapid fall off of the $\Delta(1232)$ contribution continues into this region of momentum transfer and that other resonances