Physical Review Letters
We report the first measurement of the double-spin asymmetry A(LT) for charged pion electroproduction in semi-inclusive deep-inelastic electron scattering on a transversely polarized He-3 target. The kinematics focused on the valence quark region, 0.16 < x < 0.35 with 1.4 < Q(2) < 2.7 GeV2. The corresponding neutron A(LT) asymmetries were extracted from the measured He-3 asymmetries and proton over He-3 cross section ratios using the effective polarization approximation. These new data probe the transverse momentum dependent parton distribution function g(1T)(q) and therefore provide access to quark spin-orbit correlations. Our results indicate a positive azimuthal asymmetry for pi(-) production on He-3 and the neutron, while our pi(+) asymmetries are consistent with zero.
Huang, J., Allada, K., Dutta, C., Katich, J., Qian, X., Wang, Y., ... & Benmokhtar, F. (2012). Beam-Target Double-Spin Asymmetry A LT in Charged Pion Production from Deep Inelastic Scattering on a Transversely Polarized He 3 Target at 1.4< Q 2< 2.7 GeV 2. Physical review letters, 108(5), 052001.