| Abstract: |
| The spin boson model describes a two-state quantum system (the spin) which is linearly coupled to a bosonic quantum field. Using a Feynman--Kac formula, the vacuum expectation of the semigroup generated by the Hamiltonian of the model can be described by a one-dimensional Ising model. In this talk, we discuss how the existence of ground states in the spin boson model can be investigated by studying the long-range behavior of the Ising correlation function. This especially includes the recent proof for a phase transition of the spin boson model with respect to the strength of the spin-field coupling. |
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