Measurement of Strange Quark Contributions to the Nucleon's Form Factors at Q^2=0.230 (GeV/c)^2

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dc.creatorA4 Collaboration
dc.creatorMaas, F. E.
dc.creatorAchenbach, P.
dc.creatorAulenbacher, K.
dc.creatorBaunack, S.
dc.creatorCapozza, L.
dc.creatorDiefenbach, J.
dc.creatorGrimm, K.
dc.creatorImai, Y.
dc.creatorHammel, T.
dc.creatorvon Harrach, D.
dc.creatorKabuss, E. -M.
dc.creatorKothe, R.
dc.creatorLee, J. H.
dc.creatorLorente, A.
dc.creatorGinja, A. Lopes
dc.creatorNungesser, L.
dc.creatorSchilling, E.
dc.creatorStephan, G.
dc.creatorWeinrich, C.
dc.creatorAltarev, I.
dc.creatorArvieux, J.
dc.creatorCollin, B.
dc.creatorFrascaria, R.
dc.creatorGuidal, M.
dc.creatorKunne, R.
dc.creatorMarchand, D.
dc.creatorMorlet, M.
dc.creatorOng, S.
dc.creatorvan de Wiele, J.
dc.creatorKowalski, S.
dc.creatorPlaster, B.
dc.creatorSuleiman, R.
dc.creatorTaylor, S.
dc.date2004-01-16
dc.date.accessioned2026-07-07T10:50:47Z
dc.date.available2026-07-07T10:50:47Z
dc.descriptionWe report on a measurement of the parity-violating asymmetry in the scattering of longitudinally polarized electrons on unpolarized protons at a $Q^2$ of 0.230 (GeV/c)^2 and a scattering angle of θ_e = 30^o - 40^o. Using a large acceptance fast PbF_2 calorimeter with a solid angle of ΔΩ= 0.62 sr the A4 experiment is the first parity violation experiment to count individual scattering events. The measured asymmetry is A_{phys} =(-5.44 +- 0.54_{stat} +- 0.27_{\rm sys}) 10^{-6}. The Standard Model expectation assuming no strangeness contributions to the vector form factors is $A_0=(-6.30 +- 0.43) 10^{-6}$. The difference is a direct measurement of the strangeness contribution to the vector form factors of the proton. The extracted value is G^s_E + 0.225 G^s_M = 0.039 +- 0.034 or F^s_1 + 0.130 F^s_2 = 0.032 +- 0.028.
dc.description5 pages, 3 figures, submitted to Phys. Rev. Letters on Dec 11, 2003
dc.identifierhttps://arxiv.org/abs/nucl-ex/0401019
dc.identifierhttp://arxiv.org/abs/nucl-ex/0401019
dc.identifierPhys.Rev.Lett.93:022002,2004
dc.identifierdoi:10.1103/PhysRevLett.93.022002
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/184645
dc.subjectNuclear Experiment
dc.titleMeasurement of Strange Quark Contributions to the Nucleon's Form Factors at Q^2=0.230 (GeV/c)^2
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