On Existence of Ground States in the Spin Boson Model

TL;DR

This paper proves the existence of ground states in the massless spin boson model without infrared regularization, using a non-perturbative compactness approach applicable for any coupling strength under certain boundedness conditions.

Contribution

It establishes the existence of ground states in a massless spin boson model without infrared regularization, advancing understanding of quantum field models.

Findings

Ground states exist in the massless spin boson model without infrared regularization.

The proof is non-perturbative and relies on a compactness argument.

Applicability for arbitrary coupling constants under bounded second derivative of energy.

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.