1,246 research outputs found
Quantization of spontaneously broken gauge theory based on the BFT-BFV Formalism
We quantize the spontaneously broken abelian U(1) Higgs model by using the
improved BFT and BFV formalisms. We have constructed the BFT physical fields,
and obtain the first class observables including the Hamiltonian in terms of
these fields. We have also explicitly shown that there are exact form
invariances between the second class and first class quantities. Then,
according to the BFV formalism, we have derived the corresponding Lagrangian
having U(1) gauge symmetry. We also discuss at the classical level how one
easily gets the first class Lagrangian from the symmetry-broken second class
Lagrangian.Comment: 16 pages, latex, final version published in Mod. Phys. Lett.
Vergleichende Untersuchung der endokrinen Ophthalmopathie mittels Ultrasonographie, Computertomographie und Fischbioassay
Bei 35 Patienten mit endokriner Ophthalmopathie (eO) wurde zu den Parametern der SchilddrĂŒsenfunktion (T3, T4, TBI, TRH-Test), dem Szintigramm und der Bestimmung der SchilddrĂŒsenantikörper ergĂ€nzend die Ultrasonographie (A-scan) und Computertomographie (CT) der Orbita, sowie der Nachweis exophthalmogener SerumaktivitĂ€t im Fischbioassay durchgefĂŒhrt. Charakteristische Sonogramme fĂŒr eine eO fanden sich in 26 FĂ€llen. Die CT ergab bei 24 von 33 Patienten die Verdickung der musculi recti mediales und/oder der musculi recti laterales, sowie bei 17 Patienten eine Verdichtung im Bereich der Orbitaspitze. Im retrobulbĂ€ren Bindegewebe zeigte sich nach Kontrastmittelgabe keine signifikante Dichtezunahme. Mit beiden Verfahren zusammen waren nur bei 2 Patienten die Kriterien einer eO nicht erfĂŒllt. Die exophthalmogene SerumaktivitĂ€t wurde in der IgG-Fraktion im Fischbioassay nachgewiesen; die Trefferquote war mit 69% relativ hoch. Zur Diagnostik der eO kann jedoch der Fischbioassay nicht empfohlen werden
Recursive Construction of Generator for Lagrangian Gauge Symmetries
We obtain, for a subclass of structure functions characterizing a first class
Hamiltonian system, recursive relations from which the general form of the
local symmetry transformations can be constructed in terms of the independent
gauge parameters. We apply this to a non-trivial Hamiltonian system involving
two primary constraints, as well as two secondary constraints of the Nambu-Goto
type.Comment: 10 pages, Late
Symplectic embedding and Hamilton-Jacobi analysis of Proca model
Following the symplectic approach we show how to embed the Abelian Proca
model into a first-class system by extending the configuration space to include
an additional pair of scalar fields, and compare it with the improved Dirac
scheme. We obtain in this way the desired Wess-Zumino and gauge fixing terms of
BRST invariant Lagrangian. Furthermore, the integrability properties of the
second-class system described by the Abelian Proca model are investigated using
the Hamilton-Jacobi formalism, where we construct the closed Lie algebra by
introducing operators associated with the generalized Poisson brackets.Comment: 24 page
A New Look at the Axial Anomaly in Lattice QED with Wilson Fermions
By carrying out a systematic expansion of Feynman integrals in the lattice
spacing, we show that the axial anomaly in the U(1) lattice gauge theory with
Wilson fermions, as determined in one-loop order from an irrelevant lattice
operator in the Ward identity, must necessarily be identical to that computed
from the dimensionally regulated continuum Feynman integrals for the triangle
diagrams.Comment: 1 figure, LaTeX, 18 page
Thermal Quantum Fields in Static Electromagnetic Backgrounds
We present and discuss, at a general level, new mathematical results on the
spatial nonuniformity of thermal quantum fields coupled minimally to static
background electromagnetic potentials. Two distinct examples are worked through
in some detail: uniform (parallel and perpendicular) background electric and
magnetic fields coupled to a thermal quantum scalar field.Comment: 22 page
A novel suture method to place and adjust peripheral nerve catheters
We have developed a peripheral nerve catheter, attached to a needle, which works like an adjustable suture. We used inâplane ultrasound guidance to place 45 catheters close to the femoral, saphenous, sciatic and distal tibial nerves in cadaver legs. We displaced catheters after their initial placement and then attempted to return them to their original positions. We used ultrasound to evaluate the initial and secondary catheter placements and the spread of injectate around the nerves. In 10 cases, we confirmed catheter position by magnetic resonance imaging. We judged 43/45 initial placements successful and 42/43 secondary placements successful by ultrasound, confirmed in 10/10 cases by magnetic resonance imaging
Constraint structure of O(3) nonlinear sigma model revisited
We study the constraint structure of the O(3) nonlinear sigma model in the
framework of the Lagrangian, symplectic, Hamilton-Jacobi as well as the
Batalin-Fradkin-Tyutin embedding procedure.Comment: 17 page
Lagrange versus Symplectic Algorithm for Constrained Systems
The systematization of the purely Lagrangean approach to constrained systems
in the form of an algorithm involves the iterative construction of a
generalized Hessian matrix W taking a rectangular form. This Hessian will
exhibit as many left zero-modes as there are Lagrangean constraints in the
theory. We apply this approach to a general Lagrangean in the first order
formulation and show how the seemingly overdetermined set of equations is
solved for the velocities by suitably extending W to a rectangular matrix. As a
byproduct we thereby demonstrate the equivalence of the Lagrangean approach to
the traditional Dirac-approach. By making use of this equivalence we show that
a recently proposed symplectic algorithm does not necessarily reproduce the
full constraint structure of the traditional Dirac algorithm.Comment: 20 pages, LaTe
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