Daniel Ueltschi
Analyticity in Hubbard models
(106K, LaTeX 2e with 7 PS Figures)

ABSTRACT.  The Hubbard model describes a lattice system of quantum particles 
with local (on-site) interactions. Its free energy is analytic when 
beta t is small, or beta t^2 /U is small. Here, beta is the inverse 
temperature, U the on-site repulsion and t the hopping coefficient. 
For more general models with Hamiltonian H = V + T where V involves 
local terms only, the free energy is analytic when beta ||T|| is 
small, irrespectively of V. There exists a unique Gibbs state showing 
exponential decay of spatial correlations. These properties are 
rigorously established in this paper.