Draw graphs for self-energy and Vertex functions

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Discussion Overview

The discussion centers around the drawing of graphs for self-energy and vertex functions in the context of quantum field theory. Participants seek clarification on the representation of self-energy in terms of the fermion propagator and the implications of this representation.

Discussion Character

  • Exploratory, Technical explanation, Homework-related

Main Points Raised

  • One participant requests assistance in drawing graphs for self-energy and vertex functions, expressing confusion about the representation of self-energy solely in terms of the fermion propagator S(0).
  • The same participant questions whether the self-energy depicted is merely a vacuum bubble, indicating a need for deeper understanding.
  • Another participant notes the absence of attachments, which may hinder the discussion.
  • A subsequent post attempts to re-upload the attachments for clarity.

Areas of Agreement / Disagreement

The discussion appears unresolved, with participants expressing confusion and seeking clarification without reaching a consensus on the representations or the underlying concepts.

Contextual Notes

Limitations include the lack of visual attachments that are critical for understanding the graphs being discussed, as well as potential missing assumptions regarding the definitions of self-energy and vertex functions.

Neitrino
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Could anyone help/advise me please how to draw graphs for self-energy and Vertex functions given in attachments one and two.
In attachment one Sigma is self energy in coordinate space, S - fermion propagator, here I have one question: I was reading something where I found these exppresions, but how it can be that self-energy in attachment one is expressed only in terms of Propagator S(0), it's a just a vacuum bubble, just circle isn't it?

Irealy need someones help.
Thks a lot
 
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Any feedback please...
Or did I write something wrongly or incompletely?
 
Not that I'd be able to help with the question, anyway... but I don't see any attachments.
 
Graphs

Re-uploading the attachemnts.
 

Attachments

  • 1.pdf
    1.pdf
    11.9 KB · Views: 2,534
  • 2.pdf
    2.pdf
    15.5 KB · Views: 687

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