Measurement of Strange Quark Contributions to the Vector Form Factors of the Proton at Q2=0.22 (GeV/c)2
- Baunack, S.
- Aulenbacher, K.
- Balaguer Ríos, D.
- Capozza, L.
- Diefenbach, J.
- Gläser, B.
- Von Harrach, D.
- Imai, Y.
- Kabuß, E.-M.
- Kothe, R.
- H. Lee, J.
- Merkel, H.
- C. Mora Espí, M.
- Müller, U.
- Schilling, E.
- Stephan, G.
- Weinrich, C.
- Arvieux, J.
- A. El-Yakoubi, M.
- Frascaria, R.
- Kunne, R.
- E. Maas, F.
- Morlet, M.
- Ong, S.
- Van De Wiele, J.
- Kowalski, S.
- Prok, Y.
- Taylor, S.
Publication date
January 2009
DOI Publisher
American Physical Society (APS)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 Q2=0.22 (GeV/c)2 is reported here. The measured asymmetry is ALR=(-17.23±0.82stat±0.89syst)×10-6. The standard model prediction assuming no strangeness is A0=(-15.87±1.22)×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, GEs=0.050±0.038±0.019 and GMs=-0.14±0.11±0.11
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