Effective resonant transitions in quantum optical systems: kinematic and dynamic resonances

We show that quantum optical systems preserving the total number of excitations admit a simple classification of possible resonant transitions (including effective), which can be classified by analizying the free Hamiltonian and the corresponding integrals of motion. Quantum systems not preserving the total number of excitations do not admit such a simple classification, so that an explicit form of the effective Hamiltonian is needed to specify the allowed resonances. The structure of the resonant transitions essentially depends on the algebraic propereties of interacting subsystems.