2,374 research outputs found
Description of Gluon Propagation in the Presence of an A^2 Condensate
There is a good deal of current interest in the condensate A^2 which has been
seen to play an important role in calculations which make use of the operator
product expansion. That development has led to the publication of a large
number of papers which discuss how that condensate could play a role in a
gauge-invariant formulation. In the present work we consider gluon propagation
in the presence of such a condensate which we assume to be present in the
vacuum. We show that the gluon propagator has no on-mass-shell pole and,
therefore, a gluon cannot propagate over extended distances. That is, the gluon
is a nonpropagating mode in the gluon condensate. In the present work we
discuss the properties of both the Euclidean-space and Minkowski-space gluon
propagator. In the case of the Euclidean-space propagator we can make contact
with the results of QCD lattice calculations of the propagator in the Landau
gauge. With an appropriate choice of normalization constants, we present a
unified representation of the gluon propagator that describes both the
Minkowski-space and Euclidean-space dynamics in which the A^2 condensate plays
an important role.Comment: 28 pages, 11 figure
The Nielsen Identities for the Two-Point Functions of QED and QCD
We consider the Nielsen identities for the two-point functions of full QCD
and QED in the class of Lorentz gauges. For pedagogical reasons the identities
are first derived in QED to demonstrate the gauge independence of the photon
self-energy, and of the electron mass shell. In QCD we derive the general
identity and hence the identities for the quark, gluon and ghost propagators.
The explicit contributions to the gluon and ghost identities are calculated to
one-loop order, and then we show that the quark identity requires that in
on-shell schemes the quark mass renormalisation must be gauge independent.
Furthermore, we obtain formal solutions for the gluon self-energy and ghost
propagator in terms of the gauge dependence of other, independent Green
functions.Comment: 25 pages, plain TeX, 4 figures available upon request, MZ-TH/94-0
Search Query: Can America Accept a Right to Be Forgotten as a Publicity Right?
Search engines have profoundly changed the relationship between privacy and free speech by making personal information widely and cheaply available to a global audience. This has raised many concerns both over how online companies handle the information they collect and how regular citizens use online services to invade other people’s privacy. One way Europe has addressed this change is by providing European Union citizens with a right to petition search engines to deindex links from search results—a so-called “right to be forgotten.” If the information contained in a search result is “inadequate, irrelevant or no longer relevant,” the search engine now has an obligation to make the link unsearchable on their platform in the EU. In the United States, no such right to be forgotten exists. Many scholars have argued that such a right is irreconcilable with the First Amendment and American notions of free speech, noting that European law places a higher premium on privacy over free speech than the American constitution will allow for. Up until now, commentators have framed the right to be forgotten as a privacy right. This article posits that conceptualizing the right to be forgotten as a publicity right would make it more palatable to American lawmakers, largely due to the fact it reframes a highly theoretical moral right as a concrete economic guarantee against a search engine’s unfair use of a person’s image, name, or likeness for profit
Relativistically Covariant Symmetry in QED
We construct a relativistically covariant symmetry of QED. Previous local and
nonlocal symmetries are special cases. This generalized symmetry need not be
nilpotent, but nilpotency can be arranged with an auxiliary field and a certain
condition. The Noether charge generating the symmetry transformation is
obtained, and it imposes a constraint on the physical states.Comment: Latex file, 9 page
On the Significance of the Quantity "A Squared"
We consider the gauge potential A and argue that the minimum value of the
volume integral of A squared (in Euclidean space) may have physical meaning,
particularly in connection with the existence of topological structures. A
lattice simulation comparing compact and non-compact ``photodynamics'' shows a
jump in this quantity at the phase transition, supporting this idea.Comment: 6 pages, one figur
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