Emission of Cerenkov Radiation by Charged Particles in Stationary Geometries

The emission of the Cerenkov radiation by charged particles is analyzed for stationary metrics. Results are applied to the Kerr geometry and the scalar-tensor theories of gravity. Particular emphasis is given to Brans-Dicke theory of gravity where the Cerenkov effect turns out to be kinematically allowed. It is related to the Brans-Dicke parameter ε, and vanishes in the limit in which general relativity is recovered (ε → ∞)