ppZpjj.tex

\documentclass{standalone}
\usepackage{tikz,tikz-cd}
\usetikzlibrary{calc, decorations.pathmorphing, decorations.markings, positioning, shapes, snakes, arrows, patterns, hobby, arrows.meta}
\usepackage{amsmath}
\newcommand{\zp}{\text{Z}^{\prime}}
\newcommand{\zpm}{\text{Z}^{\prime \mu}}

%-----------------------------------------------------------
%-----------------------------------------------------------
%-----------------------------------------------------------
\begin{document}
\tikzset{
>=triangle 45,
pos=.8,
scalar/.style={decorate, dashed, draw=blue},
photon/.style={decorate, thick,decoration={snake,segment length=5,post length=1mm,pre length = 1.5mm}},
boson/.style={decorate, thick,draw=blue,decoration={snake,segment length=5,post length=1mm,pre length = 1mm}},
particle/.style={draw=black, postaction={decorate}},
fermion/.style={draw=black, postaction={decorate}, decoration={markings,mark=at position .5 with {\arrow[draw=black,scale=1.5,>=stealth]{>}}}},
antifermion/.style={draw=black, postaction={decorate},decoration={markings,mark=at position .5 with {\arrow[draw=black,scale=1.5,>=stealth]{<}}}},
gluon/.style={decorate, draw=black,decoration={coil,amplitude=4pt, segment length=5pt}},
}

\begin{tikzpicture}
        \node at (-0.1,2.9) {$\overline{q}$};
        \node at (-0.1,0.1) {$q$};
        \node at (4.2,2.9) {$j$};
        \node at (4.2,0.1) {$j$};
        \draw[antifermion] (0,2.8) to (1,1.5);
        \draw[fermion] (0,0.2) to (1,1.5);
        \draw[blue, photon] (1,1.5) to (3,1.5);
        \draw[fermion] (3,1.5) to (4,2.9);
        \draw[antifermion] (3,1.5) to (4,0.1);
        \node at (2,1.2) {\textcolor{blue}{$\zp$}};
        \node at (4.4,1.5)   {\scriptsize $ \propto i  \gamma^\mu\left(g_V^q-\gamma_5 g_A^q\right) $};
        \node at (-0.3,1.5)   {\scriptsize $  i  \gamma^\mu\left(g_V^q-\gamma_5 g_A^q\right) \propto $};
        % \node at (-1,-0.5) {\bf (a)};
  \end{tikzpicture}

  \end{document}