Einstein-Podolsky-Rosen correlations in a hybrid system

We calculate the relativistic correlation function for a hybrid system of a photon and a Dirac-particle. Such a system can be produced in decay of another spin-1/2 fermion. We show, that the relativistic correlation function, which depends on particle momenta, may have local extrema for fermion velocity of order 0.5 c. This influences the degree of violation of CHSH inequality.