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  • Final analysis of proton form factor ratio data at ▫$Q^2=4.0,\ 4.8$▫, and ▫$5.6 \ GeV^2$▫
    Puckett, A. J. R. ...
    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 ▫$Q^2 \gtrsim 1 \ \rm {GeV^2}$▫, 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 theone-photon-exchange approximation and highlighted the role of quark orbitalangular 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 ▫$3.5 \ \rm{GeV^2} \leqslant Q^2 \leqslant 5.6 \ \rm {GeV^2}$▫. 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 anoverview 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.
    Vir: Physical review. C, Nuclear physics. - ISSN 0556-2813 (Vol. 85, iss. 4, 2012, str. 045203-1-045203-26)
    Vrsta gradiva - članek, sestavni del ; neleposlovje za odrasle
    Leto - 2012
    Jezik - angleški
    COBISS.SI-ID - 2419812

    Povezava(-e):

    http://link.aps.org/doi/10.1103/PhysRevC.85.045203

vir: Physical review. C, Nuclear physics. - ISSN 0556-2813 (Vol. 85, iss. 4, 2012, str. 045203-1-045203-26)
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