%0 Journal Article
%T Quasi-particle approach for general lattice Hamiltonians
%A Patrick Navez
%A Friedemann Queisser
%A Ralf Sch¨štzhold
%J Physics
%D 2013
%I arXiv
%X In many condensed-matter systems, it is very useful to introduce a quasi-particle approach, which is based on some sort of linearization around a suitable background state. In order to be a systematic and controlled approximation, this linearization should be justified by an expansion into powers of some small control parameter. Here, we present a method for general lattice Hamiltonians with large coordination numbers Z >> 1, which is based on an expansion into powers of 1/Z. In order to demonstrate the generality of our method, we apply it to various spin systems, as well as the Bose and Fermi Hubbard model.
%U http://arxiv.org/abs/1303.4112v1