Lattice calculation of the strangeness magnetic moment of the nucleon

We report on a lattice QCD calculation of the strangeness magnetic moment of the nucleon. Our result is $G_M^s\mathrm{}\left(0\right)=-0.36\pm 0.20$. 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 $-0.097\pm 0.037{\mu }_N$ 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 $-0.68\pm 0.04$ 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.