Competing local and non-local phase correlations in systems with resonant pairing: The Boson-Fermion scenario

Julius Ranninger

Centre de Recherches sur les Tres Basses Temperatures

There is a variety of systems showing a well pronounced cross-over behavior between what characterizes the weak and the strong coupling regime and where this cross-over physics can be paraphrased in terms of strong correlations involving the dynamical variables which control those extreme limits. We consider here fermionic systems which, due to some mediating bosonic fields, such as phonons or spin fluctuations, show intrinsic binary resonant scattering features in this cross-over regime and which, as a consequence, imply strong local phase correlations between pairs of uncorrelated itinerant Fermions and localized locally bound Fermion pairs (bipolarons, holon pairs, Feshbach resonant induced diatomic molecular gases in traps). The question we shall address here is how such local phase correlations have to be modified in order to enable a long range phase coherence between such bosonic fields and ultimately give rise to superfluid, respectively, Mott insulating phases.