HQET Feynman Rule: QCD Interaction Vertex Explained

In summary, the vertex HQET Feynman rule is given by igTijvμ\frac{1}{1+\slashed{v}} with the reasoning for vμ being due to the QCD interaction vertex between two heavy quark propagators, which are \frac{1+\slashed{v}}{2v.k}. This can also be written as vμ\frac{1+\slashed{v}}{2}=\frac{1+\slashed{v}}{2}γμ\frac{1+\slashed{v}}{2}. However, the question arises whether the vertex rule should be the same as in QCD, with the only difference being the heavy quark propagator.
  • #1
Elmo
35
6
TL;DR Summary
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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  • #2
and for some reason latex is not supported in this box, or am I missing something ?
 
  • #3

1. What is HQET Feynman Rule?

HQET Feynman Rule is a mathematical framework used in quantum field theory to describe the interactions between quarks and gluons in quantum chromodynamics (QCD). It is based on the principles of the Feynman diagram technique, which allows for the calculation of scattering amplitudes and cross sections in particle physics.

2. How does HQET Feynman Rule explain QCD interaction vertex?

HQET Feynman Rule provides a set of rules for constructing and evaluating Feynman diagrams that represent the interactions between quarks and gluons in QCD. This includes the QCD interaction vertex, which is the point where two or more particles interact and exchange gluons. By following the rules of HQET Feynman Rule, the QCD interaction vertex can be calculated and used to make predictions about the behavior of particles in high-energy collisions.

3. What are the advantages of using HQET Feynman Rule?

One of the main advantages of using HQET Feynman Rule is its ability to accurately describe the complex interactions between quarks and gluons in QCD. It also allows for the calculation of higher-order corrections to scattering amplitudes, making it a powerful tool for making precise predictions in particle physics experiments. Additionally, the Feynman diagram technique is a visual and intuitive way to understand the underlying physics of particle interactions.

4. Are there any limitations to HQET Feynman Rule?

While HQET Feynman Rule is a powerful tool, it is not without its limitations. One major limitation is that it only applies to perturbative calculations, meaning that it cannot be used to describe the behavior of strongly interacting particles. Additionally, it does not take into account the effects of quantum gravity, which is necessary for understanding interactions at very high energies.

5. How is HQET Feynman Rule used in experimental particle physics?

HQET Feynman Rule is used extensively in experimental particle physics to make predictions about the outcomes of high-energy collisions. By calculating the QCD interaction vertex and other relevant quantities, scientists can compare their predictions to experimental data and test the validity of the theory. This helps to improve our understanding of the fundamental building blocks of the universe and the forces that govern their interactions.

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