%0 Journal Article
%T Dispersive spectrum and orbital order of spinless p-band fermions in an optical lattice
%A Xiancong Lu
%A E. Arrigoni
%J Physics
%D 2009
%I arXiv
%R 10.1103/PhysRevB.79.245109
%X We study single-particle properties of a spinless p-band correlated fermionic gas in an optical lattice by means of a variational cluster approach (VCA). The single-particle spectral function is almost flat at half-filling and develops a strongly dispersive behavior at lower fillings. The competition between different orbital orderings is studied as a function of filling. We observe that an ``antiferromagnetic'' orbital order develops at half-filling and is destroyed by doping the system evolving into a disordered orbital state. At low filling limit, we discuss the possibility of ``ferromagnetic'' orbital order by complementing the VCA result with observations based on a trial wave function. We also study the behavior of the momentum distribution for different values of the on-site interaction. Finally, we introduce an integration contour in the complex plane which allows to efficiently carry out Matsubara-frequency sums.
%U http://arxiv.org/abs/0902.0388v2