Revisiting the dynamics of a charged spinning body in curved spacetime

Abstract We analyse the motion of the spinning body (in the pole–dipole approximation) in the gravitational and electromagnetic fields described by the Mathisson–Papapetrou–Dixon–Souriau equations. First, we define a novel spin condition for the body with the magnetic dipole moment proportional to spin, which generalizes the one proposed by Ohashi–Kyrian–Semerák for gravity. As a result, we get the whole family of charged spinning particle models in the curved spacetime with remarkably simple dynamics (momentum and velocity are parallel). Applying the reparametrization procedure, for a specific dipole moment, we obtain equations of motion with constant mass and gyromagnetic factor. Next, we show that these equations follow from an effective Hamiltonian formalism, previously interpreted as a classical model of the charged Dirac particle.