164 research outputs found
Application of the Worldline Path Integral Method to the Calculation of Inverse Mass Expansions
Higher order coefficients of the inverse mass expansion of one-loop effective
actions are obtained from a one-dimensional path integral representation. For
the case of a massive scalar loop in the background of both a scalar potential
and a (non Abelian) gauge field explicit results to in the proper time
parameter are presented.Comment: 6 pages, LaTeX. Talk given at 5th International Workshop on Software
Engineering and Artificial Intelligence for High Energy and Nuclear Physics
(AIHENP96), Lausanne (Switzerland), 2-6 September 199
An Improved Heat Kernel Expansion from Worldline Path Integrals
The one--loop effective action for the case of a massive scalar loop in the
background of both a scalar potential and an abelian or non--abelian gauge
field is written in a one--dimensional path integral representation. From this
the inverse mass expansion is obtained by Wick contractions using a suitable
Green function, which allows the computation of higher order coefficients. For
the scalar case, explicit results are presented up to order O(T**8) in the
proper time expansion. The relation to previous work is clarified.Comment: 13 pages, Plain TEX, no figure
The Higher Derivative Expansion of the Effective Action by the String Inspired Method. Part II
We apply the string inspired worldline formalism to the calculation of the
higher derivative expansion of one-loop effective actions in non-Abelian gauge
theory. For this purpose, we have completely computerized the method, using the
symbolic manipulation programs FORM, PERL and M. Explicit results are given to
sixth order in the inverse mass expansion, reduced to a minimal basis of
invariants specifically adapted to the method. Detailed comparisons are made
with other gauge-invariant algorithms for calculating the same expansion. This
includes an explicit check of all coefficients up to fifth order.Comment: 37 pages, LaTeX, 3 figures, typos corrected, to appear in Ann. Phys.
(N.Y.
17-jähriger Mann mit akuten Bauchschmerzen, Hämatochezie und Exanthem
Zusammenfassung: Ein 17-jähriger Patient stellte sich mit kolikartigen abdominellen Schmerzen und Diarrhö vor. Als weitere Symptome traten Petechien, Arthralgien und eine Hämatochezie auf. Sonographisch bestand eine auffällige Ileozökalregion. Endoskopisch fand sich eine Ileitis terminalis, und histologisch zeigte sich hier eine leukozytoklastische Vaskulitis mit IgA-Ablagerungen. Die Kasuistik zeigt exemplarisch die mehrzeitige klinische Manifestation der Purpura Schönlein-Henoch und deren Verlau
Zero modes, beta functions and IR/UV interplay in higher-loop QED
We analyze the relation between the short-distance behavior of quantum field
theory and the strong-field limit of the background field formalism, for QED
effective Lagrangians in self-dual backgrounds, at both one and two loop. The
self-duality of the background leads to zero modes in the case of spinor QED,
and these zero modes must be taken into account before comparing the
perturbative beta function coefficients and the coefficients of the
strong-field limit of the effective Lagrangian. At one-loop this is familiar
from instanton physics, but we find that at two-loop the role of the zero
modes, and the interplay between IR and UV effects in the renormalization, is
quite different. Our analysis is motivated in part by the remarkable simplicity
of the two-loop QED effective Lagrangians for a self-dual constant background,
and we also present here a new independent derivation of these two-loop
results.Comment: 15 pages, revtex
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