Extrapolation formulas for neutron EDM calculations in lattice QCD

Lattice QCD is rapidly progressing toward being able to reliably compute the electric dipole moment of the neutron as a function of the strong CP-violating parameter θ¯. Present day calculations are performed at unphysical values of the light quark masses, in volumes that are not exceptionally large and at lattice spacings that are not exceptionally small. We use chiral perturbation theory to determine the leading contributions to the neutron electric dipole moment at finite volume, and in partially-quenched calculations.