Field-theoretical model inspired by adiabatic-ansatz eigenvalue problems

We suggest an insight into level dynamics of classically nonintegrable quantum systems. When several nonintegrability parameters are varied in a Hamiltonian, the desymmetrized energy spectrum generally exhibits degeneracies. In this case the fundamental equation of level dynamics is altered as follows: (i) Euclidean ‘‘space-time’’ coordinates are needed instead of a single ‘‘time’’ coordinate; (ii) gauge structures around diabolical degenerate points are incorporated into level dynamics. With these changes we obtain an alternative field-theoretical model for interacting energy surfaces.