Large-Angle Quasielastic Electron-Deuteron Scattering

Abstract

Nucl. Phys. B22, 131 (1970). 1 9 0 . Czyiewski and M. Szeptycka, Phys. Lett. 25B, 482 (1967). 2 0 B r u x e l l e s -~~~~-~r a c o w Collaboration, A. Eskreys et al. , Nucl. Phys. (to be published).Measurements of differential cross sections for quasielastic electron-deuteron scattering e + de + p + n have been made in which recoil protons were detected in coincidence with the scattered electrons. The ratios of the elastic electron-neutron to the electron-proton scattering cross sections are derived from the proton coincidence data. For comparison, these ratios are also determined from the scattered-electron momentum spectra using the peak and area methods. The theory developed by Renard, Tran Thanh Van, and LeBellac, which includes corrections for the final-state interactions, is found to explain the proton coincidence results. The present measurements, made at an electron scattering angle of 90" for four-momentum transfers of q = 7, 10, 15, and 29 F-', and at 80' for q = 45 F-', are combined with previous results to obtain the electromagnetic form factors of the neutron.

Nucleon electromagnetic form factors

“…Figure 4 shows Rosenbluth separation results performed in the 1970's as the ratio G Ep /G D , where G D is the dipole FF given below by Eq. 14; it is noteworthy that these results strongly suggest a decrease of G Ep with increasing Q 2 , a fact noted in all four references [Ber71,Pri71,Bar73,Han73]. As will be seen in section 3.4, the slope of this decrease is about half the one found in recent recoil polarization experiments.…”

“…The results from the two JLab experiments [Jon00, Pun05,Gay02] showed conclusively for the first time a clear deviation of the proton FF ratio from unity, starting at Q 2 ≃ 1 GeV 2 ; older data from [Ber71, Pri71, Bar73,Han73] showed such a decreasing ratio, but with much larger statistical and systematic uncertainties, as seen in Fig. 4.…”

“…All cross section measurements have been single arm experiments, (e, e ′ ), except three early experiments at Cambridge [Pri71,Han73] and DESY [Bar73] in which both proton and electron were detected, (e, e ′ p), and the most recent one of Qattan et al [Qat05], in which only the proton was detected, (e, p). In all cases, measured raw cross sections need to be corrected for QED processes to first order in α ∼ 1/137, before accessing the cross section corresponding to one-photon-exchange, or Born term.…”

Neural network parameterizations of electromagnetic nucleon form-factors

“…The fit to TPE corrected data is given by 1-3-1 network (violet line), the data (red points) is taken from [70]. The fit to "old Rosenbluth data" (green points) is given by 1-1-1 network (violet line), the data is taken from [71,[78][79][80][81][82][83][84][85][86]. The fit uncertainty is computed with eq.…”

“…[70]). However, to see the TPE effect we consider also the original, (called here old Rosenbluth data) G M p /µ p G D [71,[78][79][80][81][82][83][84][85][86] and G Ep /G D [71, 78-84, 87, 88] data sets. 4 The neutron form-factor data (G En and G M n ) are obtained from…”