Changes between Version 2 and Version 3 of Models/HiggsEffective
 Timestamp:
 03/28/13 18:46:49 (7 years ago)
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Models/HiggsEffective
v2 v3 30 30 == The nonpropagating auxiliary particle T == 31 31 32 To describe the fourgluonHiggs coupling a vertex with 5 external lines is needed. This can not be done with !MadGraph. However, there is a way to circumvent thisproblem by introducing nonpropagating auxiliary particles. It is possible to rewrite the fourgluon interactions as two threepoint interactions connected by the new auxiliary tensor particle (called tn internally, and shows as T in the MG diagrams, the PDG code is 99). The troublesome fivepoint interaction (between the four gluons and the Higgs) reduces then to three threepoint interactions.32 To describe the fourgluonHiggs coupling a vertex with 5 external lines is needed. This can be done with !MadGraph5 (But not with !MadGraph4). However, there is a way to circumvent the !Madgraph4 problem by introducing nonpropagating auxiliary particles. It is possible to rewrite the fourgluon interactions as two threepoint interactions connected by the new auxiliary tensor particle (called tn internally, and shows as T in the MG diagrams, the PDG code is 99). The troublesome fivepoint interaction (between the four gluons and the Higgs) reduces then to three threepoint interactions. 33 33 34 34 Notice that the color part of the fourgluon vertex is exactly like the sum of the s, t, and uchannel exchange diagram, where the exchanged particle is in the adjoint representation of color, i.e. an octet.