%0 Journal Article
%T Equilibrium states and their entropy densities in gauge-invariant C*-systems
%A N. Akiho
%A F. Hiai
%A D. Petz
%J Mathematics
%D 2004
%I arXiv
%R 10.1142/S0129055X05002352
%X A gauge-invariant C*-system is obtained as the fixed point subalgebra of the infinite tensor product of full matrix algebras under the tensor product unitary action of a compact group. In the paper, thermodynamics is studied on such systems and the chemical potential theory developed by Araki, Haag, Kastler and Takesaki is used. As a generalization of quantum spin system, the equivalence of the KMS condition, the Gibbs condition and the variational principle is shown for translation-invariant states. The entropy density of extremal equilibrium states is also investigated in relation to macroscopic uniformity.
%U http://arxiv.org/abs/math/0409601v2