Name: Bertfried Fauser (email_not_shown)
Date: 05/19/04-06:03:37 PM Z


On Wed, 19 May 2004, Bob McElrath wrote:

Dear Bob,

        thank you for your explanation. Are there Hopf algebra methods and
recently made advances also implemented in FeynCalc? The package Rafal and
I developed, benefitted is speed and conceptual design cery much from Hopf
algebraic techniques.
        From a technical point of view, its algorithmically more sound to
try to work in the Epstein-Glaser (etc pp) framework and *not* in the
momentum (Feynman graph) picture, since the physical process is split up
in an infinite series of integrals to be evaluated. AFAIK Hopf algebraic
techniques seem to be the only way to come up with concise _and_
algorithmically effective solutions.

        I am off for three weeks, and will look into FeynCalc, I can
imagine to help withits portation to AXIOM though for several personal
reasons. If you are interested in the things I have in mind, you may
consider the recent JPysA article on Quantum fieldtheory and Hopf algebra
cohomology, by Brouder,BF,Frabetti and Oeckl. Many of the calculations
there were checked by the above mentioned package, though it was _not_
designed for that purpose.

ciao,
BF.

PS:

> The "algorithms" are documented in QFT textbooks such as Peskin &
> Schroeder

Would you really make this a claim? I still think, that without expert
knowledge one cannot derive even simple results out of these sources...

% PD Dr Bertfried Fauser
% Institution: Max Planck Institut for Mathematics Leipzig <http://www.mis.mpg.de>
% Privat Docent: University of Konstanz, Physics Dept <http://www.uni-konstanz.de>
% contact |-> URL : http://clifford.physik.uni-konstanz.de/~fauser/
% Phone : Leipzig +49 341 9959 735 Konstanz +49 7531 693491



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