Summing tree graphs at threshold
نویسندگان
چکیده
منابع مشابه
Summing one-loop graphs at multiparticle threshold.
It is shown that the technique recently suggested by Lowell Brown for summing the tree graphs at threshold can be extended to calculate the loop effects. Explicit result is derived for the sum of one-loop graphs for the amplitude of threshold production of n on-mass-shell particles by one virtual in the unbroken λφ 4 theory. It is also found that the tree-level amplitude of production of n part...
متن کاملComment on “ Summing one - loop graphs at multi - particle threshold ”
The propagator of a virtual φ-field with emission of n on-mass-shell particles all being exactly at rest is calculated at the tree-level in λφ 4 theory by directly solving recursion equations for the sum of Feynman graphs. It is shown that the generating function for these propagators is equivalent to a Fourier transform of the recently found Green's function within the background-field techniq...
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Threshold graphs are a prevalent and widely studied class of simple graphs. We generalize this class of graphs to oriented graphs (directed simple graphs). We give generalizations to four of the most commonly used definitions and show their equivalence in the oriented case. We then enumerate the number of these oriented threshold graphs which relates to the Fibonacci numbers, and finish by find...
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In this paper, we introduce a class of graphs that generalize threshold graphs by introducing threshold tolerances. Several characterizations of these graphs are presented, one of which leads to a polynomial-time recognition algorithm. It is also shown that the complements of these graphs contain interval graphs and threshold graphs, and are contained in the subclass of chordal graphs called st...
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ژورنال
عنوان ژورنال: Physical Review D
سال: 1992
ISSN: 0556-2821
DOI: 10.1103/physrevd.46.r4125