Strangeness magnetic form factor of the proton in the extended chiral quark model
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 μs and the magnetic form factor (GMs) of the proton. Methods: Within an extended chiral constituent quark model, we investigate contributions from all possible five-quark components to μs and GMs (Q2) in the four-vector momentum range Q2 ≤ 1 (GeV/c)2. Probability of the strangeness component in the proton wave function is calculated employing the 3 P0 model. Results: Predictions are obtained without any adjustable parameters. Observables μs and GMs (Q2) 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 ω5 and the s s component probability.