CP violation in Compton scattering

I consider Compton scattering off the nucleon in the presence of T violation. I construct the Compton tensor that possesses these features and consider low-energy expansion of the corresponding amplitudes. It allows separation of the Born contribution that depends only on the static properties of the nucleon, such as the electric charge, the mass, the magnetic moment, and the electric dipole moment. I introduce new structure constants, the T-odd nucleon polarizabilities that parametrize the unknown non-Born part. These constants describe the response of the T-violating content of the nucleon to the external quasistatic electromagnetic field. As an estimate, I provide a heavy-baryon ChPT calculation for these new polarizabilities and discuss the implications for the experiment.