126 research outputs found
Atomic Radiative Transitions in Thermo Field Dynamics
In this work we rederive the Lamb-Retherford energy shift for an atomic
electron in the presence of a thermal radiation. Using the Dalibard, Dupont-Roc
and Cohen-Tannoudji (DDC) formalism, where physical observables are expressed
as convolutions of suitable statistical functions, we construct the
electromagnetic field propagator of Thermo Field Dynamics in the Coulomb gauge
in order to investigate finite temperature effects on the atomic energy levels.
In the same context, we also analyze the problem of the ground state stability.Comment: LaTex file, 13 pages, no figures, includes PACS numbers and minor
changes in the text where a new section has been adde
Path-ordered Phase Factors in Scalar Quantum Electrodynamics
Starting from linear equations for the complex scalar field, the two- and
three-point Green's functions are obtained in the infrared approximation. We
show that the infrared singularity factorizes in the vertex function as in
spinorial QED, reproducing in a straightforward way the result of lenghty
perturbative calculations.Comment: 11 pages, LaTe
What's Wrong with Pauli-Villars Regularization in ?
In this letter we argue that there is no ambiguity between the Pauli-Villars
and other methods of regularization in (2+1)-dimensional quantum
electrodynamics with respect to dynamical mass generation, provided we properly
choose the couplings for the regulators.Comment: 07 pages, Latex, no figure
The Causal Phase in
The operator in Fock space which describes the scattering and
particle production processes in an external time-dependent electromagnetic
potential can be constructed from the one-particle S-matrix up to a
physical phase . In this work we determine this phase for in
(2+1) dimensions, by means of causality, and show that no ultraviolet
divergences arise, in contrast to the usual formalism of .Comment: LaTex, 11 pages, no figure
- …