Strange Quark Contribution to the Proton Spin, from Elastic $\vec{e}p$ and $\nu p$ Scattering

TL;DR

This paper combines electron and neutrino scattering data to measure the strange quark contributions to the proton's vector and axial form factors, shedding light on the strange quark's role in proton spin.

Contribution

It provides the first simultaneous extraction of $G_E^s$, $G_M^s$, and $G_A^s$ over a range of $Q^2$ using combined scattering data.

Findings

First simultaneous extraction of strange form factors.

Quantitative estimates of strange quark contributions.

Insights into the strange quark role in proton spin.

Abstract

The strangeness contribution to the vector and axial form factors of the proton is presented for momentum transfers in the range 0.45 < $Q^2$ < 1.0 GeV$^2$. The results are obtained via a combined analysis of forward-scattering parity-violating elastic $\vec{e}p$ asymmetry data from the G0 and HAPPEx experiments at Jefferson Lab, and elastic $\nu p$ and $\bar{\nu}p$ scattering data from Experiment 734 at Brookhaven National Laboratory. The combination of the two data sets allows for the simultaneous extraction of $G_E^s$, $G_M^s$, and $G_A^s$ over a significant range of $Q^2$ for the very first time. Determination of the strange axial form factor $G_A^s$ is vital to an understanding of the strange quark contribution to the proton spin.