Low-Energy Theorem Approach to One-Particle Singularity in QED{2+1}

We discuss the properties of the position space fermion propagator in three dimensional QED which has been found previouly based on Ward-Takahashi-identity for soft-photon emission vertex and spectral representation.There is a new type of mass singularity which governs the long distance behaviour.It leads the propagator vanish at large distance.This term corresponds to dynamical mass in position space.Our model shows confining property and dynamical mass generation for arbitr...

We determine the position space fermion propagator in three dimensional QED based on Ward-identity and spectral representation.There is a new type of mass singularity which governs the long distance behaviour.It leads the propagator vanish at large distance more stongly than the mass term does.This term corresponds to Dynamical mass.Momentum space proagator is compared with the analysis of Schwinger-Dyson equation and our solution contains a non-perubative effects beyond the ...

We discuss the infrared and ultraviolet behavior of the fermion propagator in (2+1)-dimensional QED based on spectral representation.If we choose soft-photon exponentiation to include all orders of soft-photon emission by electron,its spectral function may be written as $e^{F}$,where $F$ is a model independent spectral function of the lowest order in the coupling constant.We evaluate the function $F$ in an analytic way and show its short and long distance behavior with an inf...

To study the infrared behaviour of the propagator, exponentiation of the lowest order spectral function has been known.We show this method is helpful in super renormalizable theory with dimension-full coupling constant.In the 1/N approximation anomalous dimension is independent of $N$,which plays an important role for confinement and pair condensation.

We discuss the structure of the dressed fermion propagator in unquenched QED3 based on spectral function of photon.In this approximation infrared divergences that appeared in quenched case turns out to be soft.The dimension full coupling constant naturally appears as an infrared mass scale in this case.We find the reliable results for the effects of vacuum polarization for the dressed fermion propagator.The lowest order fermion spectral function has logarithmically divergent ...

We investigate analytic properties of string-integrated correlation functions and propagators with emphasis on their infrared behaviour. These are relevant in various models of quantum field theory with massless fields, including QED.

In this paper we study the infra-red behaviour of a gauge invariant and physically motivated description of a charged particle in 2+1 dimensions. We show that both the mass shift and the wave function renormalisation are infra-red finite on-shell.

It is well known that the long-range nature of the Coulomb interaction makes the definition of asymptotic ``in'' and ``out'' states of charged particles problematic in quantum field theory. In particular, the notion of a simple particle pole in the vacuum charged particle propagator is untenable and should be replaced by a more complicated branch cut structure describing an electron interacting with a possibly infinite number of soft photons. Previous work suggests a Dirac pr...

Quantum electrodynamics in three spacetime dimensions, with one massless fermion species, is studied using a non-perturbative variational approach. Quantization of the theory follows Dirac's Hamiltonian procedure, with a gauge invariant factorization of the physical degrees of freedom. Due to pair condensation in the vacuum state, the symmetry of parity is spontaneously broken. As a consequence, fermionic quasi-particles propagating in the condensate can be identified and are...

In principle, calculation of a full Green's function in any field theory requires knowledge of the infinite set of multi-point Green's functions, unless one can find some way of truncating the corresponding Schwinger-Dyson equations. For the fermion and boson propagators in QED this requires an {\it ansatz} for the full three point vertex. Here we illustrate how the properties of gauge invariance, gauge covariance and multiplicative renormalizability impose severe constraints...