Evidence for Strange Quark Contributions to the Nucleon's Form Factors at $Q^2$ = 0.108 (GeV/c)$^2$

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dc.creatorMaas, F. E.
dc.creatorAulenbacher, K.
dc.creatorBaunack, S.
dc.creatorCapozza, L.
dc.creatorDiefenbach, J.
dc.creatorGläser, B.
dc.creatorHammel, T.
dc.creatorvon Harrach, D.
dc.creatorImai, Y.
dc.creatorKabuß, E. -M.
dc.creatorKothe, R.
dc.creatorLee, J. H.
dc.creatorLorente, A.
dc.creatorSchilling, E.
dc.creatorSchwaab, D.
dc.creatorSikora, M.
dc.creatorStephan, G.
dc.creatorWeber, G.
dc.creatorWeinrich, C.
dc.creatorAltarev, I.
dc.creatorArvieux, J.
dc.creatorEl-Yakoubi, M.
dc.creatorFrascaria, R.
dc.creatorKunne, R.
dc.creatorMorlet, M.
dc.creatorOng, S.
dc.creatorvan de Wiele, J.
dc.creatorKowalski, S.
dc.creatorPlaster, B.
dc.creatorSuleiman, R.
dc.creatorTaylor, S.
dc.date2004-12-14
dc.date.accessioned2026-07-07T10:50:50Z
dc.date.available2026-07-07T10:50:50Z
dc.descriptionWe report on a measurement of the parity violating asymmetry in the elastic scattering of polarized electrons off unpolarized protons with the A4 apparatus at MAMI in Mainz at a four momentum transfer value of $Q^2$ = \Qsquare (GeV/c)$^2$ and at a forward electron scattering angle of 30$^\circ < θ_e < 40^\circ$. The measured asymmetry is $A_{LR}(\vec{e}p)$ = (\Aphys $\pm$ \Deltastat$_{stat}$ $\pm$ \Deltasyst$_{syst}$) $\times$ 10$^{-6}$. The expectation from the Standard Model assuming no strangeness contribution to the vector current is A$_0$ = (\Azero $\pm$ \DeltaAzero) $\times$ 10$^{-6}$. We have improved the statistical accuracy by a factor of 3 as compared to our previous measurements at a higher $Q^2$. We have extracted the strangeness contribution to the electromagnetic form factors from our data to be $G_E^s$ + \FakGMs $G_M^s$ = \GEsGMs $\pm $ \DeltaGEsGMs at $Q^2$ = \Qsquare (GeV/c)$^2$. As in our previous measurement at higher momentum transfer for $G_E^s$ + 0.230 $G_M^s$, we again find the value for $G_E^s$ + \FakGMs $G_M^s$ to be positive, this time at an improved significance level of 2 $σ$.
dc.description4 pages, 3 figures
dc.identifierhttps://arxiv.org/abs/nucl-ex/0412030
dc.identifierhttp://arxiv.org/abs/nucl-ex/0412030
dc.identifierPhys.Rev.Lett.94:152001,2005
dc.identifierdoi:10.1103/PhysRevLett.94.152001
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/184660
dc.subjectNuclear Experiment
dc.titleEvidence for Strange Quark Contributions to the Nucleon's Form Factors at $Q^2$ = 0.108 (GeV/c)$^2$
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