Propagators

propagators.tex (33 lines)

\documentclass[tikz]{standalone}

\usepackage{mathtools}

\let\Im\relax
\DeclareMathOperator{\Im}{Im}
\let\Re\relax
\DeclareMathOperator{\Re}{Re}

\usetikzlibrary{decorations.pathmorphing}

\def\rerange{5}
\def\imrange{4}

\begin{document}
\begin{tikzpicture}[thick]

  % Axes
  \draw[->] [decorate, decoration={zigzag, segment length=4, amplitude=1, post=lineto, post length=2}] (-\rerange, 0) -- (\rerange, 0) node[below left] {$\Re(\omega)$};
  \draw[->] (0, -\imrange+1) -- (0, \imrange-1) node[below right] {$\Im(\omega)$};

  \foreach \n in {-\imrange, ..., \imrange}{%
      \node[circle, fill, inner sep=0, minimum size=5] (omega\n) at (0, 2/3*\n) {};}
  \node[left=2, align=left] (mf) at (omega3) {Matsubara\\frequencies};

  % Propagators
  \draw[red, dashed] (-\rerange, -1) -- (\rerange, -1) node[below, very near start] {advanced};
  \draw[blue, dashed] (-\rerange, 1) -- (\rerange, 1) node[above, very near start] {retarded};
  \draw[orange, dashed] (-\rerange, -1) -- (\rerange, 1) node[below right, very near end] {Feynman};

\end{tikzpicture}
\end{document}