Thumbnail Image
Item

Final analysis of proton form factor ratio data at Q(2)=4.0, 4.8, and 5.6 GeV2

Puckett, A. J. R.
; 
Brash, E. J.
; 
Jones, M. K.
; 
Gayou, O.
; 
Pentchev, L.
; 
Perdrisat, C. F.
; 
Averett, Todd
; 
Kramer, K. M.
Abstract
Precise measurements of the proton electromagnetic form factor ratio R = mu(p)G(E)(p)/G(M)(p) using the polarization transfer method at Jefferson Lab have revolutionized the understanding of nucleon structure by revealing the strong decrease of R with momentum transfer Q(2) for Q(2) greater than or similar to 1 GeV2, in strong disagreement with previous extractions of R from cross-section measurements. In particular, the polarization transfer results have exposed the limits of applicability of the one-photon-exchange approximation and highlighted the role of quark orbital angular momentum in the nucleon structure. The GEp-II experiment in Jefferson Lab's Hall A measured R at four Q(2) values in the range 3.5 GeV2 < = Q(2) < = 5.6 GeV2. A possible discrepancy between the originally published GEp-II results and more recent measurements at higher Q(2) motivated a new analysis of the GEp-II data. This article presents the final results of the GEp-II experiment, including details of the new analysis, an expanded description of the apparatus, and an overview of theoretical progress since the original publication. The key result of the final analysis is a systematic increase in the results for R, improving the consistency of the polarization transfer data in the high-Q(2) region. This increase is the result of an improved selection of elastic events which largely removes the systematic effect of the inelastic contamination, underestimated by the original analysis.
Description
Date
2012-01-01
Journal Title
Journal ISSN
Volume Title
Publisher
Collections
Physics
Show all metadata
Download Dataset
Files
Thumbnail Image
Final_analysis_of_proton_form_factor_ratio_data_at_Q_2__4.0__4.8__and_5.6_GeV2.pdf
Adobe PDF, 1.17 MB
Rights Holder
Usage License
Embargo
Research Projects
Organizational Units
Journal Issue
Keywords
Citation
Advisor
Department
Physics
DOI
https://doi.org/10.1103/PhysRevC.85.045203
URI
https://scholarworks.wm.edu/handle/internal/774
Embedded videos