Edit and compile if you like:
\documentclass[tikz]{standalone}\usetikzlibrary{patterns}\begin{document}\begin{tikzpicture}\draw (-2,0) node[left] {$\varphi_a$} -- (0,0) -- (1.5,1.5) node[above right] {$\varphi_b$} (0,0) -- (1.5,-1.5) node[below right] {$\varphi_c$};\draw[->,yshift=5pt] (-1.7,0) -- (-0.7,0) node[midway,above] {$p_1$};\draw[<-,yshift=5pt] (0.4,0.4) -- (1.2,1.2) node[midway,above left] {$p_2$};\draw[<-,xshift=5pt] (0.4,-0.4) -- (1.2,-1.2) node[midway,above right] {$p_3$};\draw[fill=white,postaction={pattern=north east lines}] (0,0) circle (0.25) node[right=5pt] {$\Gamma_{k,abc}^{(3)}(p_1,p_2,p_3)$};\end{tikzpicture}\end{document}
Click to download: feynman-3.tex
Open in Overleaf: feynman-3.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..