Electron scattering from high-momentum neutrons in deuterium

Abstract

We report results from an experiment measuring the semiinclusive reaction 2 H(e, e p s ) in which the proton p s is moving at a large angle relative to the momentum transfer. If we assume that the proton was a spectator to the reaction taking place on the neutron in deuterium, the initial state of that neutron can be inferred. This method, known as spectator tagging, can be used to study electron scattering from high-momentum (off-shell) neutrons in deuterium. The data were taken with a 5.765 GeV electron beam on a deuterium target in Jefferson Laboratory's Hall B, using the CEBAF large acceptance spectrometer. A reduced cross section was extracted for different values of final state missing mass W * , backward proton momentum p s , and momentum transfer Q 2 . The data are compared to a simple plane wave impulse approximation (PWIA) spectator model. A strong enhancement in the data observed at transverse kinematics is not reproduced by the PWIA model. This enhancement can likely be associated with the contribution of final state interactions (FSI) that were not incorporated into the model. Within the framework of the simple spectator model, a "bound neutron structure function" F eff 2n was extracted as a function of W * and the scaling variable x * at extreme backward kinematics, where the effects of FSI appear to be smaller. For p s > 0.4 GeV/c, where the neutron is far off-shell, the model overestimates the value of F eff 2n in the region of x * between 0.25 and 0.6. A dependence of the bound neutron structure function on the neutron's "off-shell-ness" is one possible effect that can cause the observed deviation.

Semi-inclusive deep-inelastic scattering off few-nucleon systems: Tagging the EMC effect and hadronization mechanisms with detection of slow recoiling nuclei

“…Note that since at high values of Q 2 one has y ∼ y A (in the Bjorken limit y = y A ), the factor ( y y A ) 2 in the cross section (1) is often omitted (see, e.g., Ref. [8]). …”

“…[7] and p s in Refs. [8,9,11,13]). We calculated the process 2 H(e, e p)X at the kinematics of the recent JLab experiment [8,9] both in PWIA [Eq.…”

“…Experimental data on the process 2 H(e, e p)X were recently obtained at JLab [8,9] in the following kinematical regions: beam energy E e = 5.75 GeV, four-momentum transfer 1.2 Q 2 5.0 (GeV/c) 2 , recoiling proton momentum 0.28 |p p | 0.7 GeV/c, proton emission angle −0.8 cos θ p 0.7 (θ p p ·q ≡ θ p ), and invariant mass of the produced hadronic state 1.1 W X 2.7 GeV, with W 2 X = (k 1 + q) 2 = (P D − p p + q) 2 . The data have been plotted in terms of the reduced cross section…”

“…In the present paper, the SIDIS processes 2 H(e, e p)X and 3 He(e, e d)X will be analyzed in detail, presenting in the former case a comparison with recent experimental data from the Thomas Jefferson National Accelerator Facility (JLab) [8,9]. Since accurate nuclear wave functions, corresponding to realistic nucleon-nucleon (NN) interactions, e.g., the Urbana AV18 interaction [10], can be used for both the two-and three-body nuclei, our calculations can serve as a reference guide for calculations in complex nuclei.…”

Tagged spectator DIS off a polarized spin-1 target

“…The tagged spectator deuteron process has been measured in two pioneering experiments at Jefferson Lab (JLab). The Deeps experiment [1] measured at proton momenta 300 − 600 MeV, while the BONuS experiment [2,3] measured down to momenta of 70 MeV. Model calculations including the effect of final-state interactions (FSI) are available [4,5].…”