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

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.