Edit and compile if you like:
\documentclass[tikz]{standalone}\usetikzlibrary{patterns,decorations.markings}\tikzset{cross/.style={fill=white,path picture={\draw[black](path picture bounding box.south east) -- (path picture bounding box.north west)(path picture bounding box.south west) -- (path picture bounding box.north east);}},dressed/.style={fill=white,postaction={pattern=north east lines}},momentum/.style={->,semithick,yshift=5pt,shorten >=5pt,shorten <=5pt},loop/.style 2 args={thick,decoration={markings,mark=at position {#1} with {\arrow{>},\node[anchor=\pgfdecoratedangle-90,font=\footnotesize] {$p_{#2}$};}},postaction={decorate}},label/.style={thin,gray,shorten <=-1.5ex}}\def\lrad{1}\def\mrad{0.175*\lrad}\def\srad{0.15*\lrad}\begin{document}\begin{tikzpicture}[pin edge={shorten <=5*\lrad}]% Loop\draw[loop/.list={{0.125}{2},{0.125*3}{3},{0.125*5}{4},{0.125*7}{1}}] (0,0) circle (\lrad);\draw[cross] (\lrad,0) circle (\srad) node[right=6pt] {$\partial_k R_{k,ij}(p_1,p_2)$};\draw[dressed] (0,\lrad) circle (\srad) node[above=3pt] {$G_{k,jk}(p_2,p_3)$};\draw[dressed] (0,-\lrad) circle (\srad) node[below=3pt] {$G_{k,li}(p_4,p_1)$};% External line\draw (-2*\lrad,0) -- (-\lrad,0) node[pos=0.4,below] {$\varphi_a$};\draw[momentum] (-2*\lrad,0) -- (-1.25*\lrad,0) node[midway,above] {$q$};% Vertex\node (Gkakl) at (-2*\lrad,\lrad) {$\Gamma_{k,akl}^{(3)}(q,p_3,-p_4)$};\draw[label] (Gkakl.-30) -- (-\lrad,0);\draw[dressed] (-\lrad,0) circle (\mrad);\end{tikzpicture}\end{document}
Click to download: one-point.tex
Open in Overleaf: one-point.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..