A Planned Jefferson Lab Experiment on Spin-Flavor Decomposition

TL;DR

This Jefferson Lab experiment aims to measure spin-flavor asymmetries in semi-inclusive deep-inelastic scattering to improve understanding of the nucleon spin structure, focusing on valence and sea quark contributions.

Contribution

It introduces a high-statistics measurement of spin-flavor decomposition in the nucleon using semi-inclusive reactions with polarized targets and beams, including next-to-leading order analysis.

Findings

Extraction of $ riangle u_v$, $ riangle d_v$, and $ riangle ar{u} - riangle ar{d}$ distributions.

Investigation of flavor asymmetry in the polarized sea.

Enhanced understanding of nucleon spin structure.

Abstract

Experiment E04-113 at Jefferson Lab Hall C plans to measure the beam-target double-spin asymmetries in semi-inclusive deep-inelastic $\vec p(e, e^\prime h)X$ and $\vec d(e, e^\prime h)X$ reactions ($h=\pi^+, \pi^-, K^+$ or$K^-$) with a 6 GeV polarized electron beam and longitudinally polarized NH$_3$ and LiD targets. The high statistic data will allow a spin-flavor decomposition in the region of $x=0.12 \sim 0.41$ at $Q^2=1.21\sim 3.14$ GeV$^2$. Especially, leading-order and next-to-leading order spin-flavor decomposition of $\Delta u_v$, $\Delta d_v$ and $\Delta \bar{u} - \Delta \bar{d}$ will be extracted based on the measurement of the combined asymmetries $A_{1N}^{\pi^+ - \pi^-}$. The possible flavor asymmetry of the polarized sea will be addressed in this experiment.