Precision Measurements of the Nucleon Strange Form Factors at Q(2)∼0.1 GeV(2)
© 2007 The American Physical Society. The original publication is available at http://link.aps.org/doi/10.1103/PhysRevLett.98.032301
We report new measurements of the parity-violating asymmetry APV in elastic scattering of 3 GeV electrons off hydrogen and 4He targets with ⟨θlab⟩≈6.0°. The 4He result is APV=(+6.40±0.23(stat)±0.12(syst))×10-6. The hydrogen result is APV=(-1.58±0.12(stat)±0.04(syst))×10-6. These results significantly improve constraints on the electric and magnetic strange form factors GEs and GMs. We extract GEs=0.002±0.014±0.007 at ⟨Q2⟩=0.077 GeV2, and GEs+0.09GMs=0.007±0.011±0.006 at ⟨Q2⟩=0.109 GeV2, providing new limits on the role of strange quarks in the nucleon charge and magnetization distributions.