HQET Feynman Rule: QCD Interaction Vertex Explained

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SUMMARY

The HQET (Heavy Quark Effective Theory) Feynman rule for the QCD (Quantum Chromodynamics) interaction vertex is defined as igTijvμ(1/(1+slashed{v})). This formulation arises from the interaction between two heavy quark propagators, represented as (1+slashed{v})/(2v.k). The discussion emphasizes that the vertex rule should align with standard QCD principles, with the primary distinction being the heavy quark propagator's influence. The lack of LaTeX support in the forum is noted as a limitation for expressing complex equations.

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Elmo
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TL;DR
A slight confusion about HQET Feynman rules ,as stated in most texts.
Several texts state the vertex HQET Feynman rule as : igTijvμ\frac{1}{1+\slashed{v}} with the reasoning for vμ presented as being due to the QCD interaction vertex being between two heavy quark propagators, which are \frac{1+\slashed{v}}{2v.k}, giving :
vμ\frac{1+\slashed{v}}{2}=\frac{1+\slashed{v}}{2}γμ\frac{1+\slashed{v}}{2}.

So in general, shouldn't the vertex rule be the same as in QCD ? The only difference being the heavy quark propagator.
 
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and for some reason latex is not supported in this box, or am I missing something ?
 

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