Abstract
New measurements of the parity-violating asymmetry in elastic scattering of 3GeV electrons off hydrogen and helium-4 targets at theta{sub lab} = 6 degrees are reported. The helium-4 result is A = (+6.40 {+-} 0.23 (stat) {+-} 0.12 (syst)) * 10{sup -6}. The hydrogen result is A = (-1.58 {+-} 0.12 (stat) {+-} 0.04 (syst)) * 10{sup -6}. The asymmetry for hydrogen is a function of a linear combination of G{sub E}{sup s} and G{sub M}{sup s}, the strange quark contributions to the electric and magnetic form factors of the nucleon respectively, and that for helium-4 is a function solely of G{sub E}{sup s}. The combination of the two measurements separates G{sub E}{sup s} and G{sub M}{sup s} and provide new limits on the role of strange quarks in the nucleon charge and magnetization distributions. We extract G{sub E}{sup s} = 0.002 {+-} 0.014 {+-} 0.007 at Q{sup 2} = 0.077 GeV{sup 2} and G{sub E}{sup s} + 0.09 G{sub M}{sup s} = 0.007 {+-} 0.011 {+-} 0.006 at Q{sup 2} = 0.109 GeV{sup 2}.
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