143 research outputs found
A New Symmetry for QED
We demonstrate that QED exhibits a previously unobserved symmetry. Some
consequences are discussed.Comment: 9 pages, MZ-TH/93-02, DIAS-STP-93-0
Coulomb gauge Gribov copies and the confining potential
We study the approach, initiated by Marinari et al., to the static
inter-quark potential based on Polyakov lines of finite temporal extent,
evaluated in Coulomb gauge. We show that, at small spatial separations, the
potential can be understood as being between two separately gauge invariant
colour charges. At larger separations Gribov copies obstruct the
non-perturbative identification of individually gauge invariant colour states.
We demonstrate, for the first time, how gauge invariance can be maintained
quite generally by averaging over Gribov copies. This allows us to extend the
analysis of the Polyakov lines and the corresponding, gauge invariant
quark-antiquark state to all distance scales. Using large scale lattice
simulations, we show that this interpolating state possesses a good overlap
with the ground state in the quark-antiquark sector and yields the full static
inter-quark potential at all distances. A visual representation of the Gribov
copies on the lattice is also presented.Comment: 22 pages, 9 figures, v2: minor changes, references adde
Reply to Comment hep-th/9509028
This is a reply to the above comment (hep-th/9509028). We argue that QED
displays a class of symmetries which may be used to select out the various
velocity dependent superselection sectors.Comment: 2 pages, plain Te
Asymptotic Dynamics in Quantum Field Theory
A crucial element of scattering theory and the LSZ reduction formula is the
assumption that the coupling vanishes at large times. This is known not to hold
for the theories of the Standard Model and in general such asymptotic dynamics
is not well understood. We give a description of asymptotic dynamics in field
theories which incorporates the important features of weak convergence and
physical boundary conditions. Applications to theories with three and four
point interactions are presented and the results are shown to be completely
consistent with the results of perturbation theory.Comment: 18 pages, 3 figure
The Structure of Screening in QED
The possibility of constructing charged particles in gauge theories has long
been the subject of debate. In the context of QED we have shown how to
construct operators which have a particle description. In this paper we further
support this programme by showing how the screening interactions arise between
these charges. Unexpectedly we see that there are two different gauge invariant
contributions with opposite signs. Their difference gives the expected result.Comment: 8 pages, LaTe
Symmetry breaking, conformal geometry and gauge invariance
When the electroweak action is rewritten in terms of SU(2) gauge invariant
variables, the Higgs can be interpreted as a conformal metric factor. We show
that asymptotic flatness of the metric is required to avoid a Gribov problem:
without it, the new variables fail to be nonperturbatively gauge invariant. We
also clarify the relations between this approach and unitary gauge fixing, and
the existence of similar transformations in other gauge theories.Comment: 11 pages. Version 2: typos corrected, discussion of Elitzur's theorem
added. Version to appear in J.Phys.
Charges in Gauge Theories
In this article we investigate charged particles in gauge theories. After
reviewing the physical and theoretical problems, a method to construct charged
particles is presented. Explicit solutions are found in the Abelian theory and
a physical interpretation is given. These solutions and our interpretation of
these variables as the true degrees of freedom for charged particles, are then
tested in the perturbative domain and are demonstrated to yield infra-red
finite, on-shell Green's functions at all orders of perturbation theory. The
extension to collinear divergences is studied and it is shown that this method
applies to the case of massless charged particles. The application of these
constructions to the charged sectors of the standard model is reviewed and we
conclude with a discussion of the successes achieved so far in this programme
and a list of open questions.Comment: 47 pages, LaTeX, 14 figures, uses feynmp, necessary Metapost files
included. Review to appear in Pramana, Journal of Physics. Minor LaTeX change
to make page numbers visible on "Letter" paper forma
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