J. Lauwers, A. Verbeure
BEC for a Coupled Two-type Hard Core Bosons Model
(42K, LATeX)

ABSTRACT.  We study a solvable model of two hard core Bose particles. A complete analysis 
is given of its equilibrium states including the proof of existence of 
Bose-Einstein condensation. The plasmon frequencies and the quantum normal 
modes corresponding to these frequencies are rigorously constructed. In 
particular we show a two-fold degeneracy of these frequencies. We show that 
all this results from spontaneous gauge symmetry breakdown.