Strange Quark Contribution to the Nucleon Spin from Electroweak Elastic Scattering Data

TL;DR

This paper investigates the strange quark's role in the nucleon's spin by analyzing electroweak scattering data to determine the strange-quark contributions to the nucleon's axial and vector form factors, providing insights into nucleon structure.

Contribution

It combines multiple experimental data sets to determine the strange-quark contributions to nucleon form factors and models their momentum-transfer dependence, advancing understanding of nucleon spin structure.

Findings

Determined strange-quark contributions to nucleon form factors at various Q^2 values.

Modeled the Q^2-dependence of these form factors using simple functional forms.

Provided predictions for future measurements to improve understanding.

Abstract

The total contribution of strange quarks to the intrinsic spin of the nucleon can be determined from a measurement of the strange-quark contribution to the nucleon's elastic axial form factor. We have studied the strangeness contribution to the elastic vector and axial form factors of the nucleon, using elastic electroweak scattering data. Specifically, we combine elastic $\nu p$ and $\bar{\nu} p$ scattering cross section data from the Brookhaven E734 experiment with elastic $ep$ and quasi-elastic $ed$ and $e$-$^4$He scattering parity-violating asymmetry data from the SAMPLE, HAPPEx, G0 and PVA4 experiments. We have not only determined these form factors at individual values of momentum-transfer ($Q^2$), but also have fit the $Q^2$-dependence of these form factors using simple functional forms. We present the results of these fits, along with some expectations of how our knowledge of these form factors can be improved with data from Fermilab experiments.