Electroweak properties of two-nucleon systems in lattice QCD

We discuss a method by which lattice QCD simulations can be used to determine the electroweak properties of two-nucleon systems. In particular, we demonstrate that numerical calculations of two-particle energy levels in a finite volume immersed in background electroweak fields can determine the deuteron magnetic moment, the cross-section for thermal neutron capture np→dγ and the cross-section for neutrino breakup of the deuteron, νd→npν. The last of these processes is only poorly constrained experimentally and will provide a large source of uncertainty in future extractions of neutrino mass and mixing parameters from the Sudbury Neutrino Observatory.