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

Abstract

We report the first measurement of the double-spin asymmetry $A_{LT}$ for charged pion electroproduction in semi\nobreakdash-inclusive deep\nobreakdash-inelastic electron scattering on a transversely polarized ${}^3$He target. The kinematics focused on the valence quark region, $0.16<x<0.35$ with $1.4<Q^2<2.7{\text{GeV}}^2$. The corresponding neutron $A_{LT}$ asymmetries were extracted from the measured ${}^3$He asymmetries and proton over ${}^3$He 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 ${}^3$He and the neutron, while our ${\pi }^{+}$ asymmetries are consistent with zero.

6 pages, 2 figures, 1 tables, published in PRL