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Physical Review Letters






022502- (1-6)


We report the first measurement of the target-normal single-spin asymmetry in deep-inelastic scattering from the inclusive reaction 3He↑(e, e')X on a polarized 3He gas target. Assuming time-reversal invariance, this asymmetry is strictly zero in the Born approximation but can be nonzero if two-photon-exchange contributions are included. The experiment, conducted at Jefferson Lab using a 5.89 GeV electron beam, covers a range of 1.7 < W < 2.9 GeV, 1.0 < Q2 < 4.0 GeV2 and 0.16 < x < 0.65. Neutron asymmetries were extracted using the effective nucleon polarization and measured proton-to-3He cross-section ratios. The measured neutron asymmetries are negative with an average value of (-1.09 ± 0.38) x 10-2for invariant mass W > 2 GeV, which is nonzero at the 2.89σ level. Our measured asymmetry agrees both in sign and magnitude with a two-photon-exchange model prediction that uses input from the Sivers transverse momentum distribution obtained from semi-inclusive deep-inelastic scattering.


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Original Publication Citation

Katich, J., Qian, X., Zhao, Y. X., Allada, K., Aniol, K., Annand, J. R. M., . . . Zong, X. (2014). Measurement of the target-normal single-spin asymmetry in deep-inelastic scattering from the reaction ³He↑(e,e')X. Physical Review Letters, 113(2), 022502. doi:10.1103/PhysRevLett.113.022502

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