Talk:Correlation function (quantum field theory)

Just terrible!

And what do all these symbols mean? Another person (of many!!!!) on Wikipedia living in his/her own small world? — Preceding unsigned comment added by Koitus~nlwiki (talk • contribs) 14:28, 27 October 2020 (UTC)[reply]

Redirect to "Propagator"?

This article is very lacking. I suggest to redirect this page to Propagator instead. Hersle (talk) 11:12, 18 June 2021 (UTC)[reply]

Complete rewrite

This is a very important topic in QFT (if not one of the most fundamental ones), so it deserves to have a good article about it (and certainly should not be deleted). Therefore I tried to at least do a reasonable job of this. The key aspects of the topic as I see it are: 1. its definition via (in a sense) canonical quantization, and via the path integral, 2. how one can calculate the correlation functions using Wick's theorem, via Feynman rules, and via generating functionals (mild overlap with the page on effective action here is unfortunate but inevitable for logical flow of either article), 3. relation to the S-matrix via the LSZ formula and especially how exactly the matrix element is related to the Fourier transform of the momentum space amputated correlation function.

The article can also be extended possibly in a further direction of looking at how correlation functions come up in other QFTs such as their role in conformal field theory, topological QFT, or in string theory. (OpenScience709 (talk) 12:00, 30 November 2021 (UTC))[reply]

On relation to moments

I am deleting the newly written section "On relation to moments" (although I am open to discussion concerning it's merits). My arguments for deleting it are the following: a third of it is a redundant rephrasing of what is found previously in the article, a third of it is unnecessary detail into the point its making, and the last third is the point itself, which is a bit inaccurate considering that we are dealing with time-ordered correlators of quantum operators not just plain correlators of classical fields. The discussion would be more accurate for correlation functions used in statistical mechanics.

I'm instead opting for condensing the key point of this section into a sentence or two in the rest of the article. OpenScience709 (talk) 16:43, 15 February 2023 (UTC)[reply]

I do think that it is important, since it gives some mathematical connection between things. Gershonavi (talk) 14:32, 17 February 2023 (UTC)[reply]

Ok, but then what specifically should the section say? Cause I don't think that the way it was written was accurate and it was additionally very imprecise. QFT correlation functions aren't simply the correlation functions between random variables; QFT is not a classical theory of random fields. That's statistical field theory. QFT correlation functions are a Wick rotated version of statistics correlators I suppose? I do actually agree that maybe we should try to elucidate the connection though, but the proposed text did not do that. Additionally, please provide a source for the connection between the two? We really need a source to back up any claims we make. Best, OpenScience709 (talk) 22:47, 17 February 2023 (UTC)[reply]