0 Casimir energy and dilute dielectric ball

General formalism of quantum field theory and addition theorem for Bessel functions are applied to derive formula for CasimirPolder energy of interaction between a polarizable particle and a dilute dielectric ball. The equivalence of dipole-dipole interaction and Casimir energy for dilute homogeneous dielectrics is shown. A novel method is used to derive Casimir energy of a dilute dielectric ball without divergences in calculations. Physically realistic model of a dilute ball is discussed. Different approaches to the calculation of Casimir energy of a dielectric ball are reviewed. PACS numbers: 03.70.+k, 11.10.Gh, 12.20.-m, 12.20.Ds, 42.50.Lc ∗E-mail: [email protected] 1