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Center for Nonlinear Studies |
I will present a functional renormalization-group method that treats interacting fermions that are also coupled to bosonic modes. It takes into account retardation effects and the presence of multiple energy scales. It is applicable systems in which the Fermi energy of the free fermionic part is the largest energy scale. It allows the study of the stability of the Fermi liquid state and its instabilities toward other complex phases. I will discuss results for systems of cold fermionic atoms in the presence of a BEC condensate of bosonic atoms. A rich phase diagram emerges due to the interplay of two contributions to the effective fermion-fermion interaction: the on-site instantaneous Hubbard-like repulsion and a long-range retarded attractive interaction mediated by fluctuations of the BEC. When this system is on an optical lattice, the lattice geometry and the fermion filling fraction also play an important role.
Host: Eddy Timmermans, CNLS