We report a direct lattice QCD calculation of the strange nucleon electromagnetic form factors GEs and GMs in the kinematic range 0≤Q2≲1.2GeV2. For the first time, both GEs and GMs are shown to be nonzero with high significance. This work uses closer-to-physical lattice parameters than previous calculations, and achieves an unprecedented statistical precision by implementing a recently proposed variance reduction technique called hierarchical probing. We perform model-independent fits of the form factor shapes using the z-expansion and determine the strange electric and magnetic radii and magnetic moment. We compare our results to parity-violating electron-proton scattering data and to other theoretical studies.
@article{arxiv.1505.01803,
title = {High-precision calculation of the strange nucleon electromagnetic form factors},
author = {Jeremy Green and Stefan Meinel and Michael Engelhardt and Stefan Krieg and Jesse Laeuchli and John Negele and Kostas Orginos and Andrew Pochinsky and Sergey Syritsyn},
journal= {arXiv preprint arXiv:1505.01803},
year = {2015}
}