PRECISION MEASUREMENT OF THE PROTON AND DEUTERON SPIN STRUCTURE FUNCTIONS g_2

摘要

We measured the spin structure functions g_2~p and g_2~d in the range 0.02 ≤ x ≤ 0.8 and 0.7 ≤ Q~2 ≤ 20 GeV~2 by scattering 29.1 and 32.3 GeV longitudinally polarized electrons from transversely polarized NH_3 and ~6LiD targets. g_2 approximately follows the twist-2 Wandzura- Wilczek calculation. The twist-3 reduced matrix elements d_2~p and d_2~n are less than two standard deviations from zero. The data are inconsistent with the Burkhardt-Cottingham sum rule if there is no pathological behavior as x → 0. The Efrerriov-Leader-Teryaev integral is consistent with zero.