Nucleon strangeness form factors fromNf=2+1clover fermion lattice QCD

Abstract

We present the ${N}_{f}=2+1$ clover fermion lattice QCD calculation of the nucleon strangeness form factors. We evaluate disconnected insertions using the Z(4) stochastic method, along with unbiased subtractions from the hopping parameter expansion. We find that increasing the number of nucleon sources for each configuration improves the signal significantly. We obtain ${G}_{M}^{s}(0)=\ensuremath{-}0.017(25)(07)$, where the first error is statistical, and the second is the uncertainties in ${Q}^{2}$ and chiral extrapolations. This is consistent with experimental values, and has an order of magnitude smaller error.