Comparison of Polarization Observables in Electron Scattering from the Proton and Deuteron

Milbrath, Brian D.; McIntyre, Justin I.; Armstrong, Christopher; Barkhuff, D.; Bertozzi, W.; Chen, J. P.; Dale, D.; Dodson, G.; Dow, K.; Epstein, M. B.; Farkhondeh, M.; Finn, John M.; Gilad, S.; Jones, M.; Joo, K. S.; Kelly, James; Kowalski, S.; Lourie, R.; Madey, R.; Margaziotis, D. J.; Markowitz, P.; Mertz, C.; Mitchell, J.; Perdrisat, C. F.; Punjabi, V.; Qin, L.; Rutt, P. M.; Sarty, A. J.; Tieger, D.; Tschalaer, C.; Turchinetz, W.; Ulmer, P. E.; Verst, S.P. Van; Warren, G.; Weinstein, L. B.; Woo, R. J.

doi:10.1103/physrevlett.80.452

Cited by 152 publications

(92 citation statements)

References 30 publications

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“…Next, the recoil polarization method to measure the proton e.m. FF was used at MIT-Bates laboratory [Mil98,Bar99]. In this experiment the proton FF ratio G Ep /G M p was obtained for a free proton and a bound proton in a deuterium target at two Q 2 values, 0.38 and 0.5 GeV 2 using polarization transfer from longitudinally polarized electron to the proton in the target, and measuring the polarization of the recoiling proton with a focal plane polarimeter (FPP).…”

Section: Proton Form Factor Measurements With Polarization Experimentsmentioning

confidence: 99%

Nucleon electromagnetic form factors

Perdrisat

Punjabi

Vanderhaeghen

2007

Progress in Particle and Nuclear Physics

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474

583

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There has been much activity in the measurement of the elastic electromagnetic proton and neutron form factors in the last decade, and the quality of the data has been greatly improved by performing double polarization experiments, in comparison with previous unpolarized data. Here we review the experimental data base in view of the new results for the proton, and neutron, obtained at MIT-Bates, MAMI, and JLab. The rapid evolution of phenomenological models triggered by these high-precision experiments will be discussed, including the recent progress in the determination of the valence quark generalized parton distributions of the nucleon, as well as the steady rate of improvements made in the lattice QCD calculations.

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Section: Proton Form Factor Measurements With Polarization Experimentsmentioning

confidence: 99%

Nucleon electromagnetic form factors

Perdrisat

Punjabi

Vanderhaeghen

2007

Progress in Particle and Nuclear Physics

Self Cite

474

583

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“…Taking the recoil-polarization and polarized-target results from Refs. [50][51][52][53][54][55][56][57][58][59][60][61][62], we parameterize the data with a simple inverse polynomial and find that the form factor ratio is well parameterized as:…”

Section: Extraction Of the Form Factors And Tpementioning

confidence: 99%

Flavor decomposition of the nucleon electromagnetic form factors at lowQ2

2015

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Background The spatial distribution of charge and magnetization within the proton is encoded in the elastic form factors.These have been precisely measured in elastic electron scattering, and the combination of proton and neutron form factors allows for the separation of the up-and down-quark contributions.Purpose In this work, we extract the proton and neutron form factors from world's data with an emphasis on precise new data covering the low-momentum region, which is sensitive to the large-scale structure of the nucleon. From these, we separate the up-and down-quark contributions to the proton form factors.Method We combine cross section and polarization measurements of elastic electron-proton scattering to separate the proton form factors and two-photon exchange (TPE) contributions. We combine the proton form factors with parameterization of the neutron form factor data and uncertainties to separate the up-and down-quark contributions to the proton's charge and magnetic form factors.Results The extracted TPE corrections are compared to previous phenomenological extractions, TPE calculations, and direct measurements from the comparison of electron and positron scattering. The flavor-separated form factors are extracted and compared to models of the nucleon structure.Conclusions With the inclusion of the precise new data, the extracted TPE contributions show a clear change of sign at low Q 2 , necessary to explain the high-Q 2 form factor discrepancy while being consistent with the known Q 2 → 0 limit. We find that the new Mainz data yield a significantly different result for the proton magnetic form factor and its flavorseparated contributions. We also observe that the RMS radius of both the up-and down-quark distributions are smaller than the RMS charge radius of the proton.

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“…Followed by that, the proton form factor measurements using recoil polarimetry were carried out at MIT-Bates [45,67] and MAMI [68,69]. Due to limited statistics and kinematics coverage, the ratio values were in agreement within uncertainties with the unpolarized measurements.…”

Section: Introductionmentioning

confidence: 98%

“…The polarization of the beam is defined as: 45) where N + and N − are the number of electrons with their spin parallel and antiparallel to their momentum respectively. Therefore, with a polarized electron beam, the leptonic tensor is modified and a new γ matrix is introduced:…”

Section: Rosenbluth Cross Sectionmentioning

confidence: 99%

High Precision Measurement of the Proton Elastic Form Factor Ratio at Low Q<sup>2</sup>

Zhan

2010

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Experiment E08-007 measured the proton elastic form factor ratio µ p G E /G M in the range of Q 2 = 0.3−0.7(GeV/c) 2 by recoil polarimetry. Data were taken in 2008 at the Thomas Jefferson National Accelerator Facility in Virginia, USA. A 1.2 GeV polarized electron beam was scattered off a cryogenic hydrogen target. The recoil proton was detected in the left HRS in coincidence with the elasticly scattered electrons tagged by the BigBite spectrometer. The proton polarization was measured by the focal plane polarimeter (FPP).In this low Q 2 region, previous measurement from Jefferson Lab Hall A (LEDEX) along with various fits and calculations indicate substantial deviations of the ratio from unity. For this new measurement, the proposed statistical uncertainty (< 1%) was achieved. These new results are a few percent lower than expected from previous world data and fits, which indicate a smaller G Ep at this region. Beyond the intrinsic interest in nucleon structure, the new results also have implications in determining the proton Zemach radius and the strangeness form factors from parity violation experiments.

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Comparison of Polarization Observables in Electron Scattering from the Proton and Deuteron

Cited by 152 publications

References 30 publications

Nucleon electromagnetic form factors

Nucleon electromagnetic form factors

Flavor decomposition of the nucleon electromagnetic form factors at lowQ2

High Precision Measurement of the Proton Elastic Form Factor Ratio at Low Q<sup>2</sup>

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