Pion electroproduction measurements in the nucleon resonance region

TL;DR

This paper presents new pion electroproduction measurements in the nucleon resonance region, specifically around the $(1232)$ resonance, using Hall C spectrometers at Jefferson Lab, providing data that tests and guides theoretical models of nucleon structure.

Contribution

It reports the first measurements of pion electroproduction in this region with high precision, offering valuable data to refine theoretical models involving mesonic clouds and quark-gluon dynamics.

Findings

Results agree reasonably with existing pion cloud and chiral EFT models.

Data indicate the need for improvements in theoretical calculations.

Demonstrates the potential of Hall C spectrometers for resonance studies.

Abstract

We report new pion electroproduction measurements in the $\Delta(1232)$ resonance, utilizing the SHMS - HMS magnetic spectrometers of Hall C at Jefferson Lab. The data focus on a region that exhibits a strong and rapidly changing interplay of the mesonic cloud and quark-gluon dynamics in the nucleon. The results are in reasonable agreement with models that employ pion cloud effects and chiral effective field theory calculations, but at the same time they suggest that an improvement is required to the theoretical calculations and provide valuable input that will allow their refinements. The data illustrate the potential of the magnetic spectrometers setup in Hall C towards the study the $\Delta(1232)$ resonance. These first reported results will be followed by a series of measurements in Hall C, that will expand the studies of the $\Delta(1232)$ resonance offering a high precision insight within a wide kinematic range from low to high momentum transfers.