Albeverio S, Kondratiev Y, Minlos RA, Shchepan'uk GV. Ground state Euclidean measures for quantum lattice systems on compact manifolds. REPORTS ON MATHEMATICAL PHYSICS. 2000;45(3):419-429.Quantum lattice systems with compact spins and nearest-neighbour interactions are considered. The existence and uniqueness of the corresponding ground state Euclidean measures are proved for sufficiently small mass of the particles
