Flavor decomposition of the sea quark helicity distributions in the nucleon from semi-inclusive deep-inelastic scattering

TL;DR

This study measures double-spin asymmetries in semi-inclusive deep-inelastic scattering to extract sea quark helicity distributions, finding them consistent with zero and challenging recent flavor asymmetry predictions.

Contribution

It provides the first detailed flavor decomposition of sea quark helicity distributions using semi-inclusive data from polarized targets.

Findings

Sea quark helicity distributions are consistent with zero.

Data disfavor the predicted light quark sea flavor asymmetry.

Results improve understanding of nucleon spin structure.

Abstract

Double-spin asymmetries of semi-inclusive cross sections for the production of identified pions and kaons have been measured in deep-inelastic scattering of polarized positrons on a polarized deuterium target. Five helicity distributions including those for three sea quark flavors were extracted from these data together with re-analyzed previous data for identified pions from a hydrogen target. These distributions are consistent with zero for all three sea flavors. A recently predicted flavor asymmetry in the polarization of the light quark sea appears to be disfavored by the data.