Abstract:
The self field of a charged particle has a component that diverges at the particle. We use both coordinate and covariant approaches to compute an expansion of this singular field for generic geodesic orbits in Schwarzschild spacetime for scalar, electromagnetic and gravitational cases. We check agreement of both approaches and give, as an application, the calculation of previously unknown regularization parameters. In this socalled "modesum regularization" approach, each mode of the field is finite, while their sum diverges. The sum may be rendered finite and convergent by the subtraction of "regularisation parameters". higher order parameters lead to faster convergence int eh modesum. As a second example application, we compute high order expressions for the effective sourve approach to selfforce calculations.
