Why does the HQET vertex have a vμ factor?

[Elmo]

TL;DR

A slight confusion about HQET Feynman rules ,as stated in most texts.

Several texts state the vertex HQET Feynman rule as : igT_ijv^μ\frac{1}{1+\slashed{v}} with the reasoning for v_μ presented as being due to the QCD interaction vertex being between two heavy quark propagators, which are \frac{1+\slashed{v}}{2v.k}, giving :
v^μ\frac{1+\slashed{v}}{2}=\frac{1+\slashed{v}}{2}γ^μ\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.

 

[Elmo]

and for some reason latex is not supported in this box, or am I missing something ?

 

[PeroK]

and for some reason latex is not supported in this box, or am I missing something ?

https://www.physicsforums.com/help/latexhelp/