Department of Physics, University of Zagreb, Zagreb HR-41001, Croatia.
Phys Rev Lett. 2011 Jul 8;107(2):022501. doi: 10.1103/PhysRevLett.107.022501. Epub 2011 Jul 5.
We have measured the beam-normal single-spin asymmetries in elastic scattering of transversely polarized electrons from the proton, and performed the first measurement in quasielastic scattering on the deuteron, at backward angles (lab scattering angle of 108°) for Q² = 0.22 GeV²/c² and 0.63 GeV²/c² at beam energies of 362 and 687 MeV, respectively. The asymmetry arises due to the imaginary part of the interference of the two-photon exchange amplitude with that of single-photon exchange. Results for the proton are consistent with a model calculation which includes inelastic intermediate hadronic (πN) states. An estimate of the beam-normal single-spin asymmetry for the scattering from the neutron is made using a quasistatic deuterium approximation, and is also in agreement with theory.
我们测量了横极化电子在质子弹性散射中束法线方向的自旋不对称性，并在氘核上进行了第一个准弹性散射测量，在 Q² = 0.22 GeV²/c² 和 0.63 GeV²/c² 的后向角（实验室散射角为 108°）下，在 362 和 687 MeV 的束能下分别进行了测量。这种不对称性是由于双光子交换振幅与单光子交换振幅的干涉的虚部引起的。质子的结果与包括非弹性中间强子（πN）态的模型计算一致。使用准静态氘近似对来自中子的散射的束法线方向的自旋不对称性进行了估计，并且也与理论相符。
