Heavy Particle in a d-dimensional Fermionic Bath: A Strong Coupling Approach

We investigate the low temperature behavior of a heavy particle (mass $M$) in a fermionic bath. An effective action is considered which exactly implements the orthogonality catastrophe. It is equivalent to a model of local bosons coupling via a long-range interaction to the particle. The saddlepoint solution for the heavy particle propagator yields a finite quasiparticle weight in two and higher dimensions. In one dimension the propagator decays algebraically for long times. The saddle point approximation is valid for large $M$.