We present a unitary equivalent spin-boson Hamiltonian in which terms can be identified which contribute to the Bloch-Siegert shift, and to the level splittings at the anticrossings associated with the Bloch-Siegert resonances. First-order degenerate perturbation theory is used to develop approximate results in the case of moderate coupling for the level splitting.

Abstract. We consider a generalization of the spin-boson model in which two different two-level systems are coupled to an oscillator, under conditions where the oscillator energy is much less than the two-level system energies, and where the oscillator is highly excited. We find that the two-level system transition energy is

A variety of anomalies have been reported in recent years in fracture experiments, including neutron emission, elemental anomalies, and alpha emission. Such anomalies are similar to those studied in condensed matter nuclear science, which has been of interest to us in the development of theoretical models. In this work a brief review of the new theoretical approach is given, along with connections to both anomalies in fracture experiments and anomalies in other experiments. The fracture anomalies in this picture arise naturally as a result of the relevativistic interaction between vibrations and internal nuclear degrees of freedom, and up-conversion of vibrational quanta. A major conclusion of this work is that the elemental anomalies cannot be accounted for by disintegration as an incoherent process; since the observed products show a high degree of selectivity, while disintegration is very much non-selective. The possibility of disintegration as a coherent quantum process is introduced, and a suggestions for new experiments and measurements are put forth that can help to clarify underlying mechanisms.

Abstract. We consider a spin-boson model in which a spin 1 system is coupled to an oscillator. A unitary transformation is applied which allows a separation of terms responsible for the Bloch-Siegert shift, and terms responsible for the level splittings at anticrossings associated with Bloch-Siegert resonances. When the oscillator is highly excited, the system can maintain resonance for sequential multiphoton transitions. At lower levels of excitation, resonance cannot be maintained because energy exchange with the oscillator changes the level shift. An estimate for the critical excitation level of the oscillator is developed.

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