# Who is this "Kallen" and what does he represent, anyway?

by csmallw
Tags: kallen, represent
 P: 18 Hi all, I'm working on a Green function chapter of my dissertation, am referencing the equation, $$G(k,\omega) = \int_{-\infty}^\infty \frac{A(k,\omega')d\omega'}{\omega - \omega' + i0^+},$$ and I am trying to figure out the best way to credit it. I have noticed that condensed matter texts (Schrieffer, Mahan, for example) call it the "Lehmann" spectral representation, but Peskin and Schroeder and Wikipedia call it the "Kallen-Lehmann" spectral representation. Is there any reason I should not be also crediting Kallen for the formula above? The Peskin and Schroeder version of the equation (see p. 215) is slightly different from what I wrote above, but most of the differences seem like convention issues to me. Thanks!
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 Quote by csmallw Is there any reason I should not be also crediting Kallen for the formula above?
None. It's up to you.

Generally you should cite your source and label the equation only if you intend to refer to it by that label. If you want to name the equation, then it is appropriate to use the name most closely associated with the use you intend for the equation and the conventions of the journal the article is to appear in.

Usually you want to name an equation after someone if, by doing so, you are calling to the readers mind the justification for choosing that particular approach. Saves having to site a primary source, which may be many decades old, sometimes. So you use the name that will most have that effect on the reader.

Like we say "Newton's Laws" even though, arguably, Galileo should get primary credit because that is how people remember them and it means we don't have to cite Principia directly: everyone knows already.