  We consider a model for a massive uncharged non-relativistic particle
interacting with a massless bosonic field, widely referred to as the Nelson
model. It is well known, that an ultraviolet renormalized Hamilton operator
exists in this case. Further, due to translation-invariance, it decomposes into
fiber operators.
  In this paper, we treat the renormalized fiber operators. We give a
description of the operator and form domains and prove that the fiber operators
do not have a ground state. Our results hold for any non-zero coupling constant
and arbitrary total momentum. Our proof for the absence of ground states is a
new generalization of methods recently applied to related models. A major
enhancement we provide, is that the method can be applied to models with
degenerate ground state eigenspaces.
