The theta term in QCD sum rules and the electric dipole moment of the vector meson Original Research Article

We demonstrate that the QCD sum rule method can be successfully applied to the calculation of CP-odd electromagnetic observables induced by a vacuum θ-angle. We implement the approach in calculating the electric dipole moment of the rho meson to ∼ 30% precision, and find that the result can also be explicitly related to the vacuum topological susceptibility.