Measurement of Parton Distributions of Strange Quarks in the Nucleon from Charged-Kaon Production in Deep-Inelastic Scattering on the Deuteron

TL;DR

This paper measures the momentum and helicity distributions of strange quarks in the nucleon using charged-kaon production in deep-inelastic scattering, providing insights into the strange quark sea structure.

Contribution

It presents a novel extraction of strange quark distributions from charged-kaon data in polarized and unpolarized scattering, advancing understanding of nucleon structure.

Findings

Strange quark momentum distribution is softer than ubar and dbar.

Helicity distribution of strange quarks is consistent with zero within uncertainties.

Provides data for x in 0.02 to 0.6 and Q^2 > 1.0 GeV^2.

Abstract

The momentum and helicity density distributions of the strange quark sea in the nucleon are obtained in leading order from charged-kaon production in deep-inelastic scattering on the deuteron. The distributions are extracted from spin-averaged K+/- multiplicities, and from K+/- and inclusive double-spin asymmetries for scattering of polarized positrons by a polarized deuterium target. The shape of the momentum distribution is softer than that of the average of the ubar and dbar quarks. In the region of measurement 0.02 < x < 0.6 and Q^2 > 1.0 GeV^2, the helicity distribution is zero within experimental uncertainties.