[hal-01119617] Strangeness magnetic form factor of the proton in the extended chiral quark model

Background: Unravelling the role played by nonvalence flavors in baryons is crucial in deepen-ing 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 µ s and the magnetic form factor (G s M) of the proton. Methods: Within an extended chiral constituent quark model, we investigate contributions from all possible five-quark components to µ s and G s M (Q 2) in the four-vector momentum range Q 2 ≤ 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 µ s and G s M (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 ω 5 and the s¯ s component probability.



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