Strangeness magnetic form factor of the proton in the extended chiral quark model

TL;DR

This paper investigates the strangeness magnetic form factor of the proton using an extended chiral quark model, predicting small negative values consistent with experimental and lattice QCD data, emphasizing the importance of comprehensive five-quark component analysis.

Contribution

The study provides parameter-free predictions of the proton's strangeness magnetic form factor within an extended chiral quark model, highlighting the necessity of including all relevant five-quark configurations.

Findings

Predicted $ ext{G}_M^s(Q^2)$ is small and negative.

Results align with lattice QCD and experimental data.

Emphasizes the importance of including all five-quark contributions.

Abstract

Background: Unravelling the role played by nonvalence flavors in baryons is crucial in deepening our comprehension of QCD. Strange quark, a component of the higher Fock states in baryons, is an appropriate tool to investigate nonperturbative mechanisms generated by the pure sea quark. Purpose: Study the magnitude and the sign of the strangeness magnetic moment $\mu_s$ and the magnetic form factor ($G_M^s$) of the proton. Methods: Within an extended chiral constituent quark model, we investigate contributions from all possible five-quark components to $\mu_s$ and $G_M^s (Q^2)$ in the four-vector momentum range $Q^2 \leq 1$ (GeV/c)$^2$. Probability of the strangeness component in the proton wave function is calculated employing the $^3 P_0$ model. Results: Predictions are obtained without any adjustable parameters. Observables $\mu_s$ and $G_M^s (Q^2)$ are found to be small and negative, consistent with the lattice-QCD findings as well as with the latest data released by the PVA4 and HAPPEX Collaborations. Conclusions: Due to sizeable cancelations among different configurations contributing to the strangeness magnetic moment of the proton, it is indispensable to (i) take into account all relevant five-quark components and include both diagonal and non-diagonal terms, (ii) handle with care the oscillator harmonic parameter $\omega_5$ and the ${s \bar s}$ component probability.