Date of Original Version




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© 2012 American Physical Society

Abstract or Description

The parity-violating cross-section asymmetry in the elastic scattering of polarized electrons from unpolarized protons has been measured at a four-momentum transfer squared Q2=0.624  GeV2 and beam energy Eb=3.48  GeV to be APV=−23.80±0.78(stat)±0.36(syst) parts per million. This result is consistent with zero contribution of strange quarks to the combination of electric and magnetic form factors GsE+0.517GsM=0.003±0.010(stat)±0.004(syst)±0.009(ff), where the third error is due to the limits of precision on the electromagnetic form factors and radiative corrections. With this measurement, the world data on strange contributions to nucleon form factors are seen to be consistent with zero and not more than a few percent of the proton form factors.


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Published In

Physical Review Letters, 108, 102001.