265 research outputs found
SU(2) Colour Fields Around Static Sources
First results of an ongoing high statistics study of the colour flux
distribution around static quark sources in SU(2) gauge theory are presented.
The flux tube profiles and widths have been investigated for several quark
separations at beta=2.5 and beta=2.74. The results are tested against Michael's
sum rules.Comment: 3 pages (LaTeX) with 4 epsf incl. PS figs., To be publ. in Proc. of
Lattice '9
Distribution of the color fields around static quarks: Flux tube profiles
We report detailed calculations of the profiles of energy and action
densities in the quark-antiquark string in SU(2) lattice gauge theory.Comment: 40 pages, LSUHE 94-15
Flux-tubes in three-dimensional lattice gauge theories
Flux-tubes in different representations of SU(2) and U(1) lattice gauge
theories in three dimensions are measured. Wilson loops generate heavy
``quark-antiquark'' pairs in fundamental (), adjoint (), and
quartet () representations of SU(2). The first direct lattice
measurements of the flux-tube cross-section as a function of
representation are made. It is found that ,
to about 10\%. Results are consistent with a connection between the string
tension and suggested by a simplified flux-tube model,
[ is the gauge coupling], given
that scales like the Casimir , as observed in previous
lattice studies in both three and four dimensions. The results can discriminate
among phenomenological models of the physics underlying confinement. Flux-tubes
for singly- and doubly-charged Wilson loops in compact QED are also
measured. It is found that the string tension scales as the squared-charge and
the flux-tube cross-section is independent of charge to good approximation.
These SU(2) and U(1) simulations lend some support, albeit indirectly, to a
conjecture that the dual superconductor mechanism underlies confinement in
compact gauge theories in both three and four dimensions.Comment: 15 pages (REVTEX 2.1). Figures: 11, not included (available by
request from [email protected] by regular mail, postscript files, or one
self-unpacking uuencoded file
Non-perturbative determination of beta-functions and excited string states from lattices
We use lattice sum rules for the static quark potential to determine the
beta-function for symmetric and asymmetric lattices non-perturbatively. We also
study the colour field distributions in excited gluonic states.Comment: 9 pages, LATEX, 1 postscript figur
Connection between type B (or C) and F factorizations and construction of algebras
In a recent paper (Del Sol Mesa A and Quesne C 2000 J. Phys. A: Math. Gen. 33
4059), we started a systematic study of the connections among different
factorization types, suggested by Infeld and Hull, and of their consequences
for the construction of algebras. We devised a general procedure for
constructing satellite algebras for all the Hamiltonians admitting a type E
factorization by using the relationship between type A and E factorizations.
Here we complete our analysis by showing that for Hamiltonians admitting a type
F factorization, a similar method, starting from either type B or type C ones,
leads to other types of algebras. We therefore conclude that the existence of
satellite algebras is a characteristic property of type E factorizable
Hamiltonians. Our results are illustrated with the detailed discussion of the
Coulomb problem.Comment: minor changes, 1 additional reference, final form to be published in
JP
Fixed points and vacuum energy of dynamically broken gauge theories
We show that if a gauge theory with dynamical symmetry breaking has
non-trivial fixed points, they will correspond to extrema of the vacuum energy.
This relationship provides a different method to determine fixed points.Comment: 17 pages, uuencoded latex file, 3 figures, uses epsf and epsfig.
Submitted to Mod. Phys. Lett.
Four-quark flux distribution and binding in lattice SU(2)
The full spatial distribution of the color fields of two and four static
quarks is measured in lattice SU(2) field theory at separations up to 1 fm at
beta=2.4. The four-quark case is equivalent to a qbar q qbar q system in SU(2)
and is relevant to meson-meson interactions. By subtracting two-body flux tubes
from the four-quark distribution we isolate the flux contribution connected
with the four-body binding energy. This contribution is further studied using a
model for the binding energies. Lattice sum rules for two and four quarks are
used to verify the results.Comment: 46 pages including 71 eps figures. 3D color figures are available at
www.physics.helsinki.fi/~ppennane/pics
To what distances do we know the confining potential?
We argue that asymptotically linear static potential is built in into the
common procedure of extracting it from lattice Wilson loop measurements. To
illustrate the point, we extract the potential by the standard lattice method
in a model vacuum made of instantons. A beautiful infinitely rising linear
potential is obtained in the case where the true potential is actually
flattening. We argue that the flux tube formation might be also an artifact of
the lattice procedure and not necessarily a measured physical effect.
We conclude that at present the rising potential is known for sure up to no
more than about 0.7 fm. It may explain why no screening has been clearly
observed so far for adjoint sources and for fundamental sources but with
dynamical fermions.
Finally, we speculate on how confinement could be achieved even if the static
potential in the pure glue theory is not infinitely rising.Comment: 16 pages, 5 figures. Additional arguments presented, a new figure and
references adde
Isospin Multiplet Structure in Ultra--Heavy Fermion Bound States
The coupled Bethe--Salpeter bound state equations for a system,
where is a degenerate, fourth generation, super--heavy quark doublet,
are solved in several ladder approximation models. The exchanges of gluon,
Higgs and Goldstone modes in the standard model are calculated in the
ultra--heavy quark limit where weak and contributions are
negligible. A natural and multiplet pattern is found, with large
splittings occuring between the different weak iso--spin states when , the
quark masses, are larger than values in the range ,
depending on which model is used. Consideration of ultra--heavy quark lifetime
constraints and mass splitting constraints are reviewed to establish the
plausibility of lifetime and mass degeneracy requirements assumed for this
paper.Comment: 20 pages, 7 figures (hard copy available upon request), report#
KU-HEP-93-2
Supersymmetry in quantum mechanics: An extended view
The concept of supersymmetry in a quantum mechanical system is extended,
permitting the recognition of many more supersymmetric systems, including very
familiar ones such as the free particle. Its spectrum is shown to be
supersymmetric, with space-time symmetries used for the explicit construction.
No fermionic or Grassmann variables need to be invoked. Our construction
extends supersymmetry to continuous spectra. Most notably, while the free
particle in one dimension has generally been regarded as having a doubly
degenerate continuum throughout, the construction clarifies taht there is a
single zero energy state at the base of the spectrum.Comment: 4 pages, 4 figure
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