Speaker
Description
In inclusive polarized lepton-nucleon deep-inelastic scattering, the twist-3 matrix element $d_2$ is defined as the third moment of a linear combination of the spin-structure functions $g_1$ and $g_2$. It is sensitive to quark-gluon correlations in the nucleon and has been interpreted as an average color Lorentz force acting on the struck quark, due to the remnant diquark system. While the neutron $d_2$ ($d_2^n$) has been measured by several experiments, previous extractions have required evolving $g_1$ and $g_2$ to common $Q^2$ because the relevant observables were obtained over a broad $Q^2$ range. Moreover, $d_2^n$ at high $Q^2$ has remained inconclusive due to the limited statistics. To evaluate $d_2^n$ more precisely, we measured double-spin asymmetries and unpolarized cross sections at two nearly constant $Q^2$ values, $\sim$3.0 GeV$^2$ and $\sim$6.0 GeV$^2$, with high statistics in inelastic scattering of longitudinally polarized electrons from polarized $^{3}$He nuclei, using the HMS and SHMS spectrometers in Hall C at Jefferson Lab. Our data provide a significantly improved determination of $d_2^n$ at intermediate and high $Q^2$ and offer a stringent test of lattice QCD. In this talk, we will present the analysis status and preliminary results.
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