Radiative decay versus photonic Jahn-Teller distortion of molecular states

For the Wigner-Weisskopf-Dicke Hamiltonian, the probability for the upper of two molecular levels to decay, under spontaneous emission of a photon, is analyzed as a function of time. Normal decay yields a quasi-Lorentzian line shape. "Anomalous decay," i.e., a nonvanishing survival probability of the initial state, occurs when level separation is smaller than the level shift and is identified as absence of any transitions, due to a Jahn-Teller-analogous symmetry breaking with two ground states corresponding to left- or right-handed phases (inequivalent representations of the canonical commutation relations for the field). Critical slowing down of the decay results in a line shape ω^-1(lnω)^-2 as ω↓0.