Seminar

[ICTP info point]

From: bassi at ictp.trieste.it
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Joint D.F.T. and I.N.F.N. seminar

FRIDAY, 22 September 2006 - 3:00 p.m.
Room 239, Main building - 2nd floor

Dr. Dirk-Andre' Deckert
Ludwig-Maximilians Universitaet, Muenchen

TITLE:
"The Source of Ultraviolet Divergences in Quantum Field Theories"

Abstract:
In my talk I will review one major problem in relativistic quantum 
field theory (QFT), namely the ultraviolet divergence appearing in the 
equations of motion of the fields. By examining a simple example model 
from QFT together with its classical analogue we shall see that the 
quantum field theoretic as well as the classical divergence of the 
total energy are in fact identical. This insight suggests looking at 
the classical theory more carefully. Therefore the current state of 
Maxwell-Lorentz's Electrodynamics for which there still does not exist 
any 'relativistic' equations of motion will we summarized. People like 
Dirac, Born, Infeld and later on Wheeler and Feynman presented ways to 
cure the classical problem. While Dirac's mass renormalization program 
and Born-Infeld's theory of electrodynamics are ad hoc mathematical 
cures of the ultraviolet problem, Wheeler and Feynman proposed a new 
theory of electrodynamics based on an old and well-known idea of 
action-at-a-distance. In the last section of my talk I will advertise 
Wheeler-Feynman Electrodynamics as the starting ground for 
investigating ways around the ultraviolet problem because of two 
reasons: first this theory is by definition free of such divergences 
while it maintains relativistic invariance, and second it is 
empirically equivalent to Dirac's mass renormalization program, which 
to some extend has been experimentally verified. It is hoped that a 
deeper understanding of Wheeler-Feynman Electrodynamics paves the way 
for formulating a quantum analogue.

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