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

Abstract

The goal of our research is to provide the exclusive ${\gamma }^{*}n(p) \rightarrow p{\pi }^{-} (p)$ reaction cross section from deuterium data. The existing ${\gamma }^{*}n \rightarrow p{\pi }^{-}$ event generator based on MAID (Drechsel et al. in Nucl Phys A 645:145, 1999) is modified to include the spectator (proton) information based via the CD-Bonn potential (Entem and Machleidt in Phys Rev C 68:041001, 2003) to simulate the quasi-free production process. With this method, the exclusive quasi-free process has been isolated successfully as demonstrated by the comparison of the spectator momentum distribution of the simulation with the missing momentum distribution of the data, and a kinematical final-state-interaction contribution factor $R_{FSI}$ is extracted directly from the data according to the ratio between the exclusive quasi-free and full cross sections. Furthermore, the corresponding structure functions are extracted from those cross sections as well. The experiment was done in Hall B at the Thomas Jefferson National Laboratory (JLab) by using the CEBAF Large Acceptance Spectrometer (CLAS) detector, the “e1e” run data off a liquid deuterium target will provide final results with a kinematic coverage for the hadronic invariant mass (W) up to $1.825\,\text {GeV}$ and in the momentum transfer ($Q^{2}$) range of 0.4–$1.0\,\text {GeV}/c^{2}$.