Tagged spectator deep-inelastic scattering off the deuteron as a tool to study neutron structure

Wim Cosyn,Misak Sargsian

doi:10.1051/epjconf/201611203001

Wim Cosyn, Misak Sargsian

Open Access

https://doi.org/10.1051/epjconf/201611203001

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Abstract

We give an overview of a model to describe deep-inelastic scattering (DIS) off the deuteron with a spectator proton, based on the virtual nucleon approximation (VNA). The model accounts for the final-state interactions (FSI) of the DIS debris with the spectator proton. Values of the rescattering cross section are obtained by fits to high-momentum spectator data. By using the so-called "pole extrapolation method", free neutron structure functions can be obtained by extrapolating low-momentum spectator proton data to the on-shell neutron pole. We apply this method to the BONuS data set and find a surprising Bjorken $x$ dependence, indicating a possible rise of the neutron to proton structure function ratio at high $x$.

Highlights

Tagged proton spectator deep-inelastic scattering (DIS) off the deuteron (e+d → e + X + ps) can be used in several ways to study the role of QCD dynamics at nucleonic length scales
We give an overview of a model to describe deep-inelastic scattering (DIS) off the deuteron with a spectator proton, based on the virtual nucleon approximation (VNA)
The model accounts for the final-state interactions (FSI) of the DIS debris with the spectator proton

Summary

Introduction

Tagged proton spectator DIS off the deuteron (e+d → e + X + ps) can be used in several ways to study the role of QCD dynamics at nucleonic length scales. One has access to the structure functions of an almost on-shell neutron. At higher proton spectator momenta, the deuteron is in a high-density configuration and medium modifications of the structure functions can be quantified. Two experiments at Jefferson Lab have measured the reaction in different kinematics: Deeps at higher spectator momenta of a few hundred MeV [1] and, BONuS at lower ones around 100 MeV [2]. We present work in a model that has been used to account for FSI mechanisms at moderate and high Bjorken x in e + d → e + X + ps [11,12,13] as well as inclusive deuteron DIS [14, 15]

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Conclusion