Talk:Feynman parametrization

Is it correct the integration of the delta?

I do not see why the upper limit of integration are u_1,...,u_{n-2} after the integration using the delta function. This form does not agree with the usual triangle loop, where after the integration with the delta one of the two remaining variables get as an upper limit, e.g., 1-x. — Preceding unsigned comment added by 2001:14BA:21DD:8AF0:62A4:4CFF:FE64:1148 (talk) 18:51, 27 February 2016 (UTC)

That's for two variables. For many this is the correct upper limit. I'm putting back this form of the integrals, as it is the one I use most often and it is perfectly equivalent. It's taken from Weinberg. Aerthis (talk) 21:18, 22 June 2016 (UTC)

Hi, I just checked on Weinberg's book, and the formula which is shown on the page as of now does not correspond to the one in weinberg's book.

The upper limit of the integral over the parameter u_i should be u_{i-1}, and in the denominator it should be (A_1 u_{n-1} + A_2(u_{n-2} - u_{n-1}) + ... + A_N (1- u_1))^n

As I see it, this section should either have a derivation of how the formula currently shown is derived from the one given in source which is cited (weinberg). In the way it is right now, there is something ambiguous as to where this formula is taken from.

In the meantime, I changed it back to match the formula (11.A.1) on page 497 of Weinberg's book. Miaoujap (talk) 11:35, 15 January 2024 (UTC)

possible expansion under GNU/FDL 1.2

This site has the proof of a slightly less general identity that might be integrated in this article. It could be a useful source for some copy-and-paste expansion of this article, as it is licensed under FDL. — Preceding unsigned comment added by Japs 88 (talk • contribs) 13:12, 28 October 2011 (UTC)

breeze?

what exactly is this making a breeze? --MarSch 12:24, 18 December 2006 (UTC)

Factorials and GAMMA-functions

Since the results are not limited to integer powers, would it not be better to alter the last two multiple integrals to have $\Gamma$-function pre-multipliers? (This would also imply what is generally true, that the method works for powers $alpha$_n whose real parts are positive.)

Note, incidentally, that this method is useful in areas well outside quantum electodynamics! (I have used them many times in other areas.) Hair Commodore 20:17, 8 August 2007 (UTC)

I have now made this change. It looks better, but the resultant formula might still be improved. Hair Commodore 19:27, 2 September 2007 (UTC)

Examples needed

This subject would be better described if an example or two were supplied. I will attempt to do so - soon(ish). Hair Commodore 17:16, 10 August 2007 (UTC)

Spelling!

Should not this page, and its brother at Schwinger parametrization have the spelling parameterization? (That's the way in which I - and many others have spelt it for many years ...) Hair Commodore 19:24, 20 August 2007 (UTC)

I think the current spelling is correct, as you say "parametric" not "parameteric", and the Wikipedia Disambiguation page is for Parametrization, not Parameterization. Finally, according to this Ngram, "Feynman parametrization" is more common option; although both are in regular use. Simon 11:16, 21 September 2022 (UTC)

Schwinger: original contribution to Feynman parameterization

According to Sylvan Schweber's extensive (and classic) book, QED and the men who made it: Dyson, Feynman, Schwinger and Tomonaga (Princeton, 1994), the classical (simple: 1/(AB)) formula for Feynman parameterization (sic!) as recorded in the main article was given to Richard Feynman by Julian Schwinger. The latter left it to Feynman to develop and use. Hair Commodore 19:22, 28 August 2007 (UTC)

Some of this historical context should be added to the article. It's on pages 445 and 453 of the above book for those looking - but it doesn't give any details about what trick Schwinger provided that Feynman used to develop his. Simon 12:07, 21 September 2022 (UTC) — Preceding unsigned comment added by S tyler (talk • contribs)