In this article we consider linear operators satisfying a generalized
commutation relation of a type of the Heisenberg-Lie algebra. It is proven that
a generalized inequality of the Hardy's uncertainty principle lemma follows.
Its applications to time operators and abstract Dirac operators are also
investigated.
In this article, linear operators satisfying anti-commutation relations are
considered. It is proven that an anti-commutative type of the
Glimm-Jaffe-Nelson commutator theorem follows.
Ground states of the so called Yukawa model is considered. The Yukawa model
describes a Dirac field interacting with a Klein-Gordon field. By introducing
both ultraviolet cutoffs and spatial cutoffs, the total Hamiltonian is defined
as a self-adjoint operator on a boson-fermion Fock space. It is shown that the
total Hamiltonian has a positive spectral gap for all values of coupling
constants. In particular the existence of ground states is proven.
In this paper we consider the Hamiltonian of quantum electrodynamics, which
describes the system of Dirac fields coupled to quantized radiation fields. We
impose ultraviolet cutoffs on the Dirac field and the radiation field, and
introduce spatial cutoffs to define the Hamiltonian as a self-adjoint operator
on a boson-fermion Fock space. Taking a scaling limit of the Hamiltonian, we
derive the effective potential.