Edit and compile if you like:
\documentclass{standalone}\usepackage{tikz-feynman}\begin{document}$\displaystyle\partial_t \frac{\partial^2 V}{\partial^2 \chi}= \raisebox{0.5ex}{\feynmandiagram [inline=(a.base)] {a [dot] -- [charged boson, quarter left, edge label=$q$] b-- [photon, quarter left] c [dot]-- [charged boson, quarter left, edge label=$q$] d [crossed dot]-- [charged boson, quarter left, edge label=$q$] a,f1 -- c,i1 -- a,};}\enskip+\enskip\raisebox{0.5ex}{\feynmandiagram [inline=(a.base)] {{i1, i2} -- a [dot]-- [charged boson, half left, edge label=$q$] b [crossed dot]-- [charged boson, half left, edge label=$q$] a,};}$\end{document}
Click to download: loops.tex
Open in Overleaf: loops.tex
This file is available on tikz.netlify.app and on GitHub and is MIT licensed.
See more on the author page of Janosh Riebesell..