title: Decay of polarons and molecules in a strongly polarized Fermi gas.
abstract: The ground state of an impurity immersed in a Fermi sea changes from a polaron to a molecule as the interaction strength is increased. We show here that the coupling between these two states is strongly suppressed due to a combination of phase-space effects and Fermi statistics, and that it vanishes much faster than the energy difference between the two states, thereby confirming the first order nature of the polaron-molecule transition. In the regime where each state is metastable, we find quasiparticle lifetimes which are much longer than what is expected for a usual Fermi liquid. Our analysis indicates that the decay rates are sufficiently slow to be experimentally observable.
authors.affiliation: Mathematical Physics, Lund Institute of Technology, P.O. Box 118, SE-22100 Lund, Sweden.
authors.forename: G M
authors.initials: GM
authors.lastname: Bruun
authors.forename: P
authors.initials: P
authors.lastname: Massignan