An upper limit to the electric dipole moment of the neutron from lattice   QCD
  A linear increase with the volume of the topological susceptibility can signal spontaneous breaking of parity and time inversion, due to a nonzero vacuum expectation value of the topological charge. Such a breaking would produce a nonzero electric dipole moment of the neutron, d_n. An upper limit to d_n is derived from numerical simulations at increasing volumes. 
B. Alles (INFN Pisa), M. D'Elia (U. Genova), A. Di Giacomo (U. Pisa)