The static gluon Green's function in a spherical bag and the Breit-Fermi interaction

We present explicit expressions for the static transversal gluon Green's function in a spherical bag and evaluate the boundary corrections to the different parts of the Breit-Fermi Hamiltonian for a heavy quark-antiquark system. We restrict ourselves here to the interaction terms and reserve the analysis of the self-interaction terms to a further study.