The Iorio–O'Carroll theorem for $N$-particle lattice Hamiltonian

The unitary equivalence of the full and free Hamiltonians for a $N$-particle quantum lattice system with the small coupling constant is proved. This result is obtained by means of the mathematical scattering theory: we prove the existence and asymptotic completeness of the wave operators. Here we construct a special representation for the exponent of the Hamiltonian.