Talk:Feynman diagram

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Representation of physical reality[edit]

This section is VERY mislwading or in any case very LACKING.

It states that " Gerard 't Hooft and Martinus Veltman gave good arguments for taking the original, non-regularized Feynman diagrams as the most succinct representation of our present knowledge about the physic" but what are these 'good arguments'?

The quote ""The Feynman graphs and rules of calculation summarize quantum field theory in a form in close contact with the experimental numbers one wants to understand. Although the statement of the theory in terms of graphs may imply perturbation theory, use of graphical methods in the many-body problem shows that this formalism is flexible enough to deal with phenomena of nonperturbative characters ..."" does NOT at all argue for 'physical reality' (not as it is now, maybe it is more clear in context) but rather that Feynmann diagrams are a good visualization of the MATH behind QFT rather than the actual 'physical reality'. — Preceding unsigned comment added by 131.175.161.14 (talk) 13:01, 28 February 2014 (UTC)

short story wrong[edit]

there is no vertical line in the diagram as cited in the 'short story'

Inclusion of the amplituhedron technique[edit]

I notice that there has been a dispute about inclusion of the new amplituhedron work into this article. I worked a bit on the Amplituhedron article when it came out. The topic is interesting in that there are popular accounts of the results and reception, but none of the papers about the technique itself are yet published. The paragraph proposed by Paul venter is based on the reference Arxiv 1212.5605. This paper has been submitted to Arxiv, but has not yet been published in a peer-reviewed journal. While Arxiv does filter out crank papers, as far as I know, WP editor consensus has never been to consider Arxiv as a reliable source. Without a reliable source for the physics itself, I don't think the amplituhedron blurb is verifiable in reliable sources. For now I recommend deleting the amplituhedron blurb with option to revisit when these techniques have been published and there are reliable sources. --Mark viking (talk) 03:49, 12 October 2013 (UTC)

There has never been agreement among WP editors about the reliability of sources and it has been acknowledged that no source is completely reliable or unreliable. Consequently using one's common sense about contentious sources is still a reasonable option. By this time it should be apparent to anyone interested in Feynman diagrams that there is a development termed amplituhedron and that it materially reduces the computational work. Thus the link between the two concepts is not fallacious. To ignore the link and insist on a peer-reviewed article to be published, leaves a large logical gap in the article that may take years before it is corrected. I'm certain that by now more 'authoritative' articles have been published, but until someone locates and cites these I feel that my contribution, flawed as some editors may think it, should stand. Paul venter (talk) 07:41, 12 October 2013 (UTC)
I'm against mentioning this in the lead, I'm not per se against saying something about it later in the article. The method has been reviewed rigorously by top physicists, so publication in a peer reviewed journal for this particular case is irrelevant. What matters a lot more is the relevance, the way you present and explain the method in this article. So, if we want to say that there exists a new technique that allows one to sum over a large number of Feynman diagrams of certain types of processes, then that can in principle be mentioned, but in a section later on in this article where one should also discuss other mathematical techniques such as this one. Count Iblis (talk) 16:42, 12 October 2013 (UTC)
In case people are interested, there is this discussion on arXiv papers.
As the amplituhedron is theoretical, we definitely need peer-reviewed published articles to support the inclusion. WP:VERIFIABILITY is more important than the heartfelt opinions that it "should" be in WP. M∧Ŝc2ħεИτlk 08:58, 13 October 2013 (UTC)
This whole arXiv thing is the mother of all red herrings here, it easily satisfies verifiability as it already has been extensively reviewed, a lot more than most peer reviewed papers ever get due to its high profile nature. It already has 47 citations, with some of the citing articles already having been published. This clearly indicates the rigorous level of review this paper already has had. Count Iblis (talk) 14:46, 13 October 2013 (UTC)
To further my opinion, it matches yours Count Iblis: don't mention the amplituhedron in the lead, but have a section somewhere titled "Other mathematical techniques" (or words to that effect) which mention the amplituhedron, Hopf algebra etc. Does this make everyone happy? M∧Ŝc2ħεИτlk 14:53, 13 October 2013 (UTC)
Yes, and that would also force editors to focus on the technical aspects of this which has been reviewed extensively. What you do not want here is the hype about this method, as that is only published in the unreliable media (blogs etc.). Count Iblis (talk) 15:08, 13 October 2013 (UTC)

There are several misunderstandings here. First of all the paper which is cited is about the positive grassmanian, which is NOT the amplituhedron. They are related, but no paper has appeared yet describing the amplituhedron, not even on the arxiv. It has appeared ONLY in talks. So the citation is wrong, and the discussion here of whether or not papers on the arxiv should be taken as sources is irrelevant. In fact I don't think there is any serious doubt on the technical validity of the amplituhedron, but even assuming it is correct I do not think it merits inclusion in the opening of an article on Feynman diagrams. It is a technical device that simplifies SOME aspects of perturbative calculations in SOME quantum field theories. It is hardly alone in this category, there are many other examples, some of which allow computation of more things in the theories they work for than the amplituhedron does in N=4 SYM. — Preceding unsigned comment added by 128.112.84.101 (talk) 17:04, 20 October 2013 (UTC)

I have removed the section from the lede until the situation is clarified. Xxanthippe (talk) 21:47, 20 October 2013 (UTC).

The description is the most clear part of the article.[edit]

The description is very clear.

It would be really helpful to an interested lay reader to work the formulation with the electron-positron annihilation example. The article has a nice clear example. Now, build on that clarity.

Thanks for including more Feynman diagrams in the article. It does help.

MiddleSchoolTeacher (talk) 03:44, 29 June 2014 (UTC)

First Feynman diagram caption[edit]

The only direction of time consistent with the labelling of this Feynman diagram is from left to right, if you have time from bottom to top as you seem to want to the electron and quark are miss-labelled and should be a positron and an anti-quark. The interaction in your description is not what is depicted, a positron does not turn into an electron when it interacts with a quark through a virtual photon. Quogle (talk) 12:31, 9 March 2015 (UTC)

Fair enough. Give me a minute, I'll fix the diagram so that it's consistent.--OCCullens (talk) 07:03, 22 March 2015 (UTC)
That is unnecessary, it is accurate as it stands, the description is entirely consistent with the diagram. Just to check you do know that the arrows for antiparticles point against the direction of time/propagation? It is possible that this is the source of confusion. Quogle (talk) 22:22, 22 March 2015 (UTC)

Greek terminology/translation of Feynman diagram-Feynogram[edit]

monolectics[edit]

  • φαϋνόγραμμα
  • φαϋνογράφημα
  • φαϋνοδιάγραμμα

periphrastic, polylectic[edit]

  • διάγραμμα Φάυνμαν

Motivation and History kaon diagram[edit]

No arrows to indicate time direction Len loker (talk) 08:44, 7 July 2016 (UTC)

This makes it one of only two diagrams on the page that are correct. Feynman diagrams don't have space/time axes. Dukwon (talk) 14:20, 22 November 2016 (UTC)
By convention time is usually read left to right, or bottom to top. MŜc2ħεИτlk 17:04, 22 November 2016 (UTC)

Dyson quote[edit]

I removed this: "However, in 2006 Dyson himself confirmed that the diagrams should be called Feynman diagrams because "he taught us how to use them".". It was added in 2011 but has never been sourced and I cannot verify it. Fences&Windows 09:09, 14 February 2017 (UTC)

I adduced the solid precise quote from Schwebber's book (op.cit), in the Alternative Names section. Feynman's heavy computational use of his eponymous spacetime diagrams as graphs of particle QED was firmed up, pedagogically, by Dyson's re-exression into QFT, and the purely symbolic abstract book-keeping device of today. Nevertheless, I personally know that Gell-Mann's jocular usage cited was not really a focussed historiographical statement. Cuzkatzimhut (talk) 19:16, 10 April 2017 (UTC)