Strange Quark Contribution to the Vector and Axial Form Factors of the Nucleon: Combined Analysis of G0, HAPPEx, and Brookhaven E734 Data

Abstract

The strange quark contribution to the vector and axial form factors of the nucleon has been determined 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 parity-violating asymmetries measured in elastic $\vec{e}p$ scattering at forward angles establish a relationship between the strange vector form factors $G_E^s$ and $G_M^s$, with little sensitivity to the strange axial form factor $G_A^s$. On the other hand, elastic neutrino scattering at low $Q^2$ is dominated by the axial form factor, with some significant sensitivity to the vector form factors as well. Combination of the two data sets allows 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. The $Q^2$-dependence of the strange axial form factor suggests that the strange quark contribution to the proton spin, $\Delta s$, is negative.

21 pages, 2 figures, 6 tables, 63 references; revised to fix minor typos and to add a missing reference; to be submitted to Physical Review C

References in corpus (8)

• Global Analysis of Helicity Parton Densities and Their Uncertainties
• Global Analysis of Nucleon Strange Form Factors at Low $Q^2$
• Quasielastic axial-vector mass from experiments on neutrino-nucleus scattering
• Isospin violation in the vector form factors of the nucleon
• Determination of the strange form factors of the nucleon from $\nu p$, $\bar{\nu }p$, and parity-violating $\vec{e}p$ elastic scattering
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• Strange nucleon form factors: Solitonic approach to $G_M^s$, $G_E^s$, ${\tilde{G}}_A^p$ and ${\tilde{G}}_A^n$ and comparison with world data
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Cited by in corpus (6)

• Flavor Structure of the Nucleon Sea
• First measurement of the strange axial coupling constant using neutral-current quasielastic interactions of atmospheric neutrinos at KamLAND
• Strange quark content of the nucleon
• Implementation and investigation of electron-nucleus scattering in the \textsc{NEUT} neutrino event generator
• Global Fit of Electron and Neutrino Elastic Scattering Data to Determine the Strange Quark Contribution to the Vector and Axial Form Factors of the Nucleon
• Quark flavor decomposition of the nucleon axial form factors