Physics Letters B
We report the most precise measurement to date of a parity-violating asymmetry in elastic electron–proton scattering. The measurement was carried out with a beam energy of 3.03 GeV and a scattering angle (θlab) = 6.0○ , with the result A PV = ( − 1.14 ± 0.24 ( stat ) ± 0.06 ( syst ) ) × 10−6 . From this we extract, at Q2 = 0.099 GeV2 , the strange form factor combination GsE + 0.080 GsM = 0.030 ± 0.025 ( stat ) ± 0.006 ( syst ) ± 0.012 ( FF ) where the first two errors are experimental and the last error is due to the uncertainty in the neutron electromagnetic form factor. This result significantly improves current knowledge of GsE and GsM at Q2 ∼ 0.1 GeV2 . A consistent picture emerges when several measurements at about the same Q2 value are combined: GsE is consistent with zero while positive values are favored for GsM, though GsE = GsM = 0 is compatible with the data at 95% C.L.
Original Publication Citation
Aniol, K. A., Armstrong, D. S., Averett, T., Benaoum, H., Bertin, P. Y., Burtin, E., . . . Zheng, X. (2006). Constraints on the nucleon strange form factors at Q2 ∼ 0.1 GeV2. Physics Letters B, 635(5–6), 275-279. doi:http://dx.doi.org/10.1016/j.physletb.2006.03.011
Aniol, K. A.; Armstrong, D. S.; Averett, T.; Benaoum, H.; Bertin, P. Y.; Burtin, E.; Cahoon, J.; Cates, G. D.; Chang, C. C.; Chao, Y.-C.; Deepa, D.; and Ibrahim, H., "Constraints on the Nucleon Strange Form Factors at Q2 ∼ 0.1 GeV2" (2006). Mechanical & Aerospace Engineering Faculty Publications. 44.