Unregularized Propagator Diagrams

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  Code

  LaTeX

\documentclass[tikz]{standalone}

\usetikzlibrary{patterns}

\def\radius{1}

\begin{document}
\begin{tikzpicture}

  % Left diagram
  \draw[thick] (0,0) circle (\radius);
  \draw (-2*\radius,0) -- (-\radius,0) (\radius,0) -- (2*\radius,0);

  \draw[fill=white,postaction={pattern=north east lines}] (\radius,0) circle (0.25*\radius) node[above right] {$\Gamma_k^{(3)}$} (-\radius,0) circle (0.25*\radius) node[above left] {$\Gamma_k^{(3)}$};

  \node at (3*\radius,0) {$-$};

  % Right diagram
  \begin{scope}[xshift=160]
    \draw[thick] (0,0) circle (\radius);
    \draw (-2*\radius,-\radius) -- (2*\radius,-\radius);

    \draw[fill=white,postaction={pattern=north east lines}] (0,-\radius) circle (0.25*\radius) node[above=5pt] {$\Gamma_k^{(4)}$};
  \end{scope}

\end{tikzpicture}
\end{document}

  Typst

#import "@preview/cetz:0.3.4": canvas, draw
#import "@preview/modpattern:0.1.0": modpattern
#import draw: line, content, circle

#set page(width: auto, height: auto, margin: 8pt)

// Define styles and constants
#let radius = 1 // \radius in original
#let vertex-rad = 0.25 * radius

// Create hatched pattern for vertices
#let hatched = modpattern(
  (.1cm, .1cm),
  std.line(start: (0%, 100%), end: (100%, 0%), stroke: 0.5pt),
  background: white,
)

// Helper function for dressed vertices
#let dressed-vertex(pos, label: none, rel-label: none, name: none, ..rest) = {
  circle(pos, radius: vertex-rad, fill: hatched, name: name)
  if label != none {
    let label-pos = if rel-label != none { (rel: rel-label, to: pos) } else { pos }
    content(label-pos, $#label$, ..rest)
  }
}

#canvas({
  // First diagram
  // Main loop
  circle((0, 0), radius: radius, stroke: 1pt, name: "loop")

  // External lines
  line((-2 * radius, 0), (-radius, 0), stroke: 1pt, name: "left-external")
  line((radius, 0), (2 * radius, 0), stroke: 1pt, name: "right-external")

  // Vertices with labels
  dressed-vertex(
    (-radius, 0),
    label: $Gamma_k^((3))$,
    rel-label: (-0.3, 0.3),
    name: "vertex-left",
    anchor: "south",
  )
  dressed-vertex(
    (radius, 0),
    label: $Gamma_k^((3))$,
    rel-label: (0.3, 0.3),
    name: "vertex-right",
    anchor: "south",
  )

  // Add minus sign between diagrams
  content((3 * radius, 0), $-$)

  // Second diagram
  // Main loop
  circle((5 * radius, 0), radius: radius, stroke: 1pt, name: "loop2")

  // External line
  line((5 * radius - 2 * radius, -radius), (5 * radius + 2 * radius, -radius), stroke: 1pt, name: "external2")

  // Four-vertex with label
  dressed-vertex(
    (5 * radius, -radius),
    label: $Gamma_k^((4))$,
    rel-label: (0, 0.35),
    name: "vertex-four",
    anchor: "south",
  )
})