Lattice calculation of the strangeness magnetic moment of the nucleon

Abstract

We report on a lattice QCD calculation of the strangeness magnetic moment of the nucleon. Our result is ${G}_{M}^{s}(0)=\ensuremath{-}0.36\ifmmode\pm\else\textpm\fi{}0.20$. The sea contributions from the u and d quarks are about 80% larger. However, they cancel to a large extent due to their electric charges, resulting in a smaller net sea contribution of $\ensuremath{-}0.097\ifmmode\pm\else\textpm\fi{}0.037{\ensuremath{\mu}}_{N}$ to the nucleon magnetic moment. As far as the neutron to proton magnetic moment ratio is concerned, this sea contribution tends to cancel out the cloud-quark effect from the $Z$ graphs and results in a ratio of $\ensuremath{-}0.68\ifmmode\pm\else\textpm\fi{}0.04$ which is close to the SU(6) relation and the experiment. The strangeness Sachs electric mean-square radius $〈{r}_{s}^{2}{〉}_{E}$ is found to be small and negative.