Dear Vladyslav and Mailing List Users,
I got stuck by something probably very trivial. In short, I wonder what is the elegant way to include the decay width in an internal propagator. I have tried to implement it as
(*after generating FA diagrams*)
ruleResonance = {
Mchi -> Sqrt[(Mchi^2 - I*Mchi*\[CapitalGamma]chi)]
};
CreateFeynAmp[diagram] /. M$FACouplings /. ruleResonance
However, after I apply FCFAConvert[], the minus sign is not picked up right. I think that is because all other minus signs have been wrapped as "-" while the one I manually inserted in front of \Gamma_{\chi} is just a regular minus sign. This causes trouble as later when I do
(amp[0] (ComplexConjugate[amp[0]])) //
FermionSpinSum[#, ExtraFactor -> 1/2] & //
DiracSimplify // Simplify// FCE // FeynAmpDenominatorExplicit
all terms with decay width inserted are not simplified.
Any input would be appreciated.
Best,
Chen
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