3,086 research outputs found
Hamiltonian approach to Yang-Mills theory in Coulomb gauge
Recent results obtained within the Hamiltonian approach to continuum
Yang-Mills theory in Coulomb gauge are reviewed.Comment: 7 pages, 2 figures, to appear in the ``Quark Confinement and the
hadron spectrum VII'' (Portugal 2006) conference proceeding
Infrared analysis of propagators and vertices of Yang--Mills theory in Landau and Coulomb gauge
The infrared behaviour of gluon and ghost propagators, ghost-gluon vertex and
three-gluon vertex is investigated for both the covariant Landau and the
non-covariant Coulomb gauge. Assuming infrared ghost dominance, we find a
unique infrared exponent in the d=4 Landau gauge, while in the d=3+1 Coulomb
gauge we find two different infrared exponents. We also show that a finite
dressing of the ghost-gluon vertex has no influence on the infrared exponents.
Finally, we determine the infrared behaviour of the three-gluon vertex
analytically and calculate it numerically at the symmetric point in the Coulomb
gauge.Comment: 25 pages, 6 figures, accepted by Phys. Rev. D, references added,
typos correcte
Analysis of reinforced concrete structures with occurrence of discrete cracks at arbitrary positions
A nonlinear analysis of in-plane loaded plates is presented, which eliminates the disadvantages of the smeared crack approach. The elements used and the computational method are discussed. An example is shown in which one or more discrete cracks are dominant
Confining Solution of the Dyson-Schwinger Equations in Coulomb Gauge
The Dyson-Schwinger equations arising from minimizing the vacuum energy
density in the Hamiltonian approach to Yang-Mills theory in Coulomb gauge are
solved numerically. A new solution is presented which gives rise to a strictly
linearly rising static quark potential and whose existence was previously
observed in the infrared analysis of the Dyson-Schwinger equations. For the new
solution we also present the static quark potential and calculate the running
coupling constant from the ghost-gluon vertex.Comment: 9 pages, 3 figures, references added
Contactless 2-dimensional laser sensor for 3-dimensional wire position and tension measurements
We have developed a contact-free 2-dimensional laser sensor with which the
position of wires can be measured in 3 dimensions with an accuracy of better
than 10 micrometer and with which the tension of the wires can be determined
with an accuracy of 0.04 N. These measurements can be made from a distance of
15 cm. The sensor consists of commercially available laser pointers, lenses,
color filters and photodiodes. In our application we have used this laser
sensor together with an automated 3 dimensional coordinate table. For a single
position measurement, the laser sensor is moved by the 3-dimensional coordinate
table in a plane and determines the coordinates at which the wires intersect
with this plane. The position of the plane itself (the third coordinate) is
given by the third axis of the measurement table which is perpendicular to this
plane. The control and readout of the table and the readout of the laser sensor
were realized with LabVIEW. The precision of the position measurement in the
plane was determined with wires of 0.2 mm and 0.3 mm diameter. We use the
sensor for the quality assurance of the wire electrode modules for the KATRIN
neutrino mass experiment. We expect that the precision is at least comparable
or better if the wires are thinner. Such a device could be well suited for the
measurement of wire chamber geometries even with more than one wire layer.Comment: 15 pages, 8 figure
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