Jaynes-Cummings model without rotating wave approximation. Asymptotics   of eigenvalues
  In this paper the perturbation theory with the frequency of transition in atom as perturbation parameter is constructed. The estimation of the reminder term of series of this perturbation theory is given. With the help of this perturbation theory we have found an exact asymptotics of eigenvalues of complete hamiltonian in the limit of high quantum numbers. It is shown that the counter-rotating terms keep a leading term but absolutely change a second term of this asymptotic. 
Eduard Tur