Abstract.
The A4 Collaboration at the MAMI accelerator in Mainz measures the parity-violating asymmetry in the cross-section of elastic scattering of longitudinally polarized electrons off unpolarized protons from which the contribution of strange sea quarks to the vector form factors of the proton can be derived. Measurements at forward angles 30° ⩽ θ ⩽ 40° and two different momentum transfers Q2 of 0.23 (GeV/c)2 and 0.11 (GeV/c)2 have been performed in the past. Measurements at backward angles 140° ⩽ θ ⩽ 150° are underway for a separate determination of the strange electric and the strange magnetic form factor at Q 2 = 0.23(GeV/c)2 .
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Baunack, S. The parity violation A4 experiment at forward and backward angles. Eur. Phys. J. A 32, 457–461 (2007). https://doi.org/10.1140/epja/i2006-10416-x
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DOI: https://doi.org/10.1140/epja/i2006-10416-x