3
4 4 4
.... .. 5 -5
------- 6-- --
10 8 99
10 8 10 10 8
11 9 11 11
12 12 12
lure 1-2. Various to draw F : :... diagrams. T, figure shows various
a certain perturbative expression for an amplitude can be graphically
represented, a tcchrniU : invented and named after nnman. To the right the
traditional F. nman diagram is shown with pro .' ."s, i.e. field correlations,
depicted '( <: and straight lines. In the figure on the left the same graph
is drawn using 't Li:.oft's double-line notation. ::: the middle is the scheme,
also by 't Hooft, which draws the Feynman diagram as a world sheet with each
numbered s ., -e area of the gr.. '. ., I:: to the ]: : '.! rs.
are contained in that description. In contrast to the work presented in this thesis. the
Lightcone ''. -ld Sheet has been investigated with an entirely different approximation
scheme, namely the so-called ,, :... 1 ', '. constitutes the next step
towards ':: ; the ::: erturbative from the new world-sheet formalism.
We will briefly discuss this method and the results for the Lightcone World Sheet
obtained from it. Although some knowledge of the Lightcone World Sheet is necessary
to understand this discussion, it still belongs here because it is really not part of the main
themes of the thesis.
T: mineain-field approximation effort to analyzing the Lightcone World Sheet model
for field theories (for simplicity, the scalar Q3 field theory) started soon after the original