Feynman Diagrams, are these allowed?

In summary, the conversation discusses the rules of thumb for diagrams involving strong, electromagnetic, and weak interactions at different energy levels. It also addresses potential issues with diagrams involving tau and antitau particles and suggests solutions for these issues.
  • #1
NumberBucket
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Homework Statement
I have drawn a couple of diagrams for each of the two following equations. Are any of them wrong? Are either preferred? I don't have much practice with drawing these...
Relevant Equations
electron + positron -> tau+ anti-tau
electron + positron -> tau-neutrino + anti-tau-neutrino
Capture1.PNG


Capture2.PNG

These are my attempts, I have found two possibilities for each, but have no idea if they're 'legal'...

Thanks in advance!
 
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  • #2
As a rule of thumb: strong > electromagnetic > weak, and tree-level > loops
While the diagrams are possible (except for the signs in the second one, check these) there is a much more important diagram for tau+antitau unless you are close to the Z energy in the collision.
The fourth diagram has additional particles that shouldn't be there.
 
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  • #3
mfb said:
As a rule of thumb: strong > electromagnetic > weak, and tree-level > loops
While the diagrams are possible (except for the signs in the second one, check these) there is a much more important diagram for tau+antitau unless you are close to the Z energy in the collision.
The fourth diagram has additional particles that shouldn't be there.
Ah ok, thanks! So would the first one be better with a photon then? And would flipping the RHS of the second one fix the charge issues?
 
  • #4
"Better" is subjective. "Stronger" at low energies: Certainly.

Yes, flipping the RHS will fix it.
 
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FAQ: Feynman Diagrams, are these allowed?

What are Feynman Diagrams?

Feynman Diagrams are graphical representations of particle interactions in quantum field theory. They were developed by physicist Richard Feynman to visualize and calculate the probabilities of different particle interactions.

How do Feynman Diagrams work?

Feynman Diagrams use arrows and lines to represent particles and their interactions. The arrows indicate the direction of time and the lines represent the particles involved. The diagrams are used to calculate the probabilities of different particle interactions by considering the conservation of energy and momentum.

Are Feynman Diagrams allowed in all branches of physics?

Yes, Feynman Diagrams are used in a variety of fields including particle physics, nuclear physics, and condensed matter physics. They are a fundamental tool in understanding and predicting particle interactions.

Can Feynman Diagrams be used to predict the behavior of particles?

Yes, Feynman Diagrams are used to calculate the probabilities of different particle interactions. By considering all possible diagrams, physicists can make predictions about the behavior of particles in different scenarios.

Are Feynman Diagrams still relevant in modern physics?

Yes, Feynman Diagrams are still widely used in modern physics. They have been adapted and expanded upon to include more complex interactions and are an important tool in understanding the behavior of particles at the subatomic level.

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