New results from the HAPPEX Experiments at Q(2)=0.1 GeV/c(2)

作者：Armstrong D S^*

来源：European Physical Journal A, 2007, 32(4): 451-455.

DOI：10.1140/epja/i2006-10394-y

The nucleon's strange electric and magnetic form factors G(E)(s) and G(M)(s) can be probed via parity-violating electron scattering. The HAPPEX Collaboration has made new measurements of the parity-violating asymmetry A(PV) in elastic scattering of 3 GeV electrons off hydro g e nand He-4 targets with approximate to 6.0 degrees For He-4 the preliminary result is A(PV) = (+ 6.43 +/- 0.23 (stat) +/- 0.22 (syst)) x 10(-6). For hydro gent h e preliminary result is A(PV) = (-1.60 +/- 0.12 (stat) +/- 0.05 (syst)) x 10(-6). From these values we extract G(E)(s) = 0.004 +/- 0.014 +/- 0.013 at < Q(2)> = 0.077 GeV/c(2), and G(E)(s) + 0.09 G(M)(s) = 0.004 +/- 0.011 +/- 0.005 at < Q(2)> = 0.109 GeV/c(2), both consistent with zero, providing stringent new limits on the role of strange quarks in the vector structure of the nucleon.

• 出版日期2007-6