This is a copy of the diagram from Wikipedia. I produced this using codes developed by me as previously instructed here with other examples. — What to do when its 2 am around here, you are fresh but nowhere to go.

Here is the code:
% Feynman diagram
% Requires PGF >= 2.0
\documentclass{article}
\usepackage[latin1]{inputenc}
\usepackage{tikz}
\usetikzlibrary{trees}
\usetikzlibrary{decorations.pathmorphing}
\usetikzlibrary{decorations.markings}
\usepackage{verbatim}
\begin{comment}
:Title: Higgs-Strahlung from Wikipedia
\end{comment}
\begin{document}
% Define styles for the different kind of edges in a Feynman diagram
\tikzset{
photon/.style={decorate, decoration={snake,amplitude=1mm, segment length=4mm}, draw=cyan},
electron1/.style={draw=blue, thick, postaction={decorate},decoration={markings,mark=at position .55 with {\arrow[draw=red]{<}}}},
electron2/.style={draw=blue, postaction={decorate},decoration={markings,mark=at position .55 with {\arrow[draw=red]{>}}}},
electron3/.style={postaction={decorate}, draw=red, dashed, thick, decoration={markings,mark=at position .55 with {\arrow[draw=red]{}}}},
}
\begin{tikzpicture}[
thick,
% Set the overall layout of the tree
level/.style={level distance=1.5cm},
level 2/.style={sibling distance=2.6cm},
level 3/.style={sibling distance=3cm}
]
%[level 1/.style={level distance=10mm},
%level 2/.style={level distance=5mm}]
\node (root)
child[grow =south west]{node{$f$} edge from parent [electron1]}
child[grow=north west]{node{$\bar{f}$} edge from parent [electron2]}
child[grow=right]{node [align=left]{W/Z}
edge from parent [photon]}
{child[grow=right]{edge from parent [photon] }
{
child[grow=south east]{ edge from parent [electron3]}
child[grow=north east]{ edge from parent [photon]}}
}
node at (root-3-1-1) {$H$}
%node at (root-3-1) {$W$}
node at (root-3-1-2) {$W/Z$}
;
\hspace{6.5 cm}
\vspace{-6 cm}
;
\end{tikzpicture}
\end{document}
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