On Existence of Ground States in the Spin Boson Model
arXiv:2102.13373 · doi:10.1007/s00220-021-04185-w
Abstract
We show the existence of ground states in the massless spin boson model without any infrared regularization. Our proof is non-perturbative and relies on a compactness argument. It works for arbitrary values of the coupling constant under the hypothesis that the second derivative of the ground state energy as a function of a constant external magnetic field is bounded.
14 pages