Baunack S, Aulenbacher K, Balaguer Ríos D, Capozza L, Diefenbach J, Gläser B, von Harrach D, Imai Y, Kabuss EM, Kothe R, Lee JH, Merkel H, Mora Espí MC, Müller U, Schilling E, Stephan G, Weinrich C, Arvieux J, El-Yakoubi MA, Frascaria R, Kunne R, Maas FE, Morlet M, Ong S, van de Wiele J, Kowalski S, Prok Y, Taylor S. Measurement of strange quark contributions to the vector form factors of the proton at Q2 = 0.22 (GeV / c)2.
PHYSICAL REVIEW LETTERS 2009;
102:151803. [PMID:
19518619 DOI:
10.1103/physrevlett.102.151803]
[Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2008] [Indexed: 05/27/2023]
Abstract
A new measurement of the parity violating asymmetry in elastic electron scattering on hydrogen at backward angles and at a four momentum transfer of Q;{2} = 0.22 (Ge V / c);{2} is reported here. The measured asymmetry is A_{LR} = (-17.23 +/- 0.82_{stat} +/- 0.89_{syst}) x 10;{-6}. The standard model prediction assuming no strangeness is A_{0} = (-15.87 +/- 1.22) x 10;{-6}. In combination with previous results from measurements at forward angles, it is possible to disentangle for the first time the strange form factors at this momentum transfer, G_{E};{s} = 0.050 +/- 0.038 +/- 0.019 and G_{M};{s} = -0.14 +/- 0.11 +/- 0.11.
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