Why do neutrons and neutrinos have arrows in Feynman diagrams?

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Discussion Overview

The discussion revolves around the interpretation of arrows in Feynman diagrams, specifically addressing the nature of what these arrows represent in terms of particle flow and conserved quantities. Participants explore the implications for neutrons and neutrinos, questioning the relationship between arrows and electric current.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants propose that arrows in Feynman diagrams represent electric current.
  • Others argue that arrows indicate the direction of matter fermions and their antiparticles, with the direction of the arrow denoting particle flow.
  • A participant expresses confusion regarding the relationship between arrows and electric current, seeking clarification on the meaning of "following matter fermions."
  • Another participant asserts that the concept of arrows representing electric current is incorrect in the context of Feynman diagrams.
  • It is suggested that arrows represent the flow of conserved charges, such as electric charge, baryon number, or lepton number.
  • A later reply questions the relevance of electric charge in specific processes, indicating that the arrows may not correlate with electric charge flow.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the interpretation of arrows in Feynman diagrams. Multiple competing views remain regarding whether arrows represent electric current or the flow of other conserved quantities.

Contextual Notes

There are limitations in the discussion regarding the definitions of terms like "electric current" and "conserved charge," as well as the specific contexts in which these interpretations apply. Some assumptions about the nature of particle interactions may also be unresolved.

thegirl
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The arrows in a Feynman diagram represent electric current. right? If this is the case then why do neutrons and neutrinos have arrows. How do they have an electric current?
 
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sorry for the spelling mistakes
 
thegirl said:
The arrows in a Feynman diagram represent electric current. right?
No they do not. They follow matter fermions (in arrow direction) or their antiparticles (against arrow direction).
The electric charge is not relevant, and an electric current is something completely different.
 
what do you mean when you say follow matter fermions, how the the arrows follow matter fermions? do you mean the direction? So the arrows do represent direction except for an antiparticle where the arrow is in the opposite to the direction?

Sorry, I'm a little lost as I was told they represented the direction the the electric current is in which is why the arrows for a particle and antiparticle where in different directions.
 
I just read up about it, and understand that they represent particle flow. So no one else has heard of the arrows representing the direction of the electric current?
 
thegirl said:
So no one else has heard of the arrows representing the direction of the electric current?
It is completely wrong for Feynman diagrams.

You can use arrows in circuit diagrams (with resistors and so on), but that has nothing to do with Feynman diagrams.
 
Arrows represent the flow of a conserved charge: it could be electric charge, baryon number, or lepton number, to give 3 examples.
 
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Avodyne said:
Arrows represent the flow of a conserved charge: it could be electric charge, baryon number, or lepton number, to give 3 examples.
Baryon number and lepton number: fine, I can see that.
Electric charge... well, consider the process "up -> down + W+" - the arrows have no relation to the flow of electric charge.
 

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