14.2 Feynman Diagrams and Feynman Rules
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(a)
(b)
Fig. 14.4 Section of P 0,3 and cubic vertex. (a) A section S 0,3 over P 0,3 reduces to a point. (b)
Fundamental cubic vertex
(a)
(b)
(c)
Fig. 14.5 Factorization of the quartic amplitude A 0,4 in the s-, t- and u-channels. (a) s-channel.
(b) t-channel. (c) u-channel