  The spin-boson model (or the dissipative two-state system) is a model for the
study of dissipation and decoherence in quantum mechanics. The spin-boson model
with Ohmic dissipation is an integrable theory, related to several other
integrable systems including the anisotropic Kondo and resonant level models.
Here we consider the problem of computing the overlaps between two ground
states corresponding to different values of parameters of the Ohmic spin-boson
Hamiltonian. We argue that this can be understood as a part of the problem of
quantizing the mKdV/sine-Gordon integrable hierarchy. The main objective of
this work is to analyze how the Anderson orthogonality affects the Yang-Baxter
integrable structure underlying the theory.
