1
\begin{tikzpicture}
  \begin{feynman}
    \vertex (a) {\(\mu^{-}\)};
    \vertex [right=of a] (b);
    \vertex [above right=of b] (f1) {\(\nu_{\mu}\)};
    \vertex [below right=of b] (c);
    \vertex [above right=of c] (f2) {\(\overline \nu_{e}\)};
    \vertex [below right=of c] (f3) {\(e^{-}\)};

    \diagram* {
      (a) -- [fermion] (b) -- [fermion] (f1),
      (b) -- [boson, edge label'=\(W^{-}\)] (c),
      (c) -- [anti fermion] (f2),
      (c) -- [fermion] (f3),
    };
  \end{feynman}
\end{tikzpicture} 

for a first-order Feynman diagram. now I want to draw diagrams that involve the photon becoming a particle anti-particle air and then giving back a photon, which then causes the scattering

1
  • Hello and welcome. Can you expand your code to be a MWE? So it contains everything it needs to compile? Also your description of the wanted result seems to need a lot of physics knowledge. I for my part do not know what you want to achieve.... Maybe a drawing would help?!
    – Sango
    Oct 9 '19 at 14:56
3

Welcome! A W^- is not a photon. You may use half left to draw one side of a loop.

\documentclass[tikz,border=3mm]{standalone}
\usepackage{tikz-feynman}
\begin{document}
\begin{tikzpicture}
  \begin{feynman}
    \vertex (a) {\(\mu^{-}\)};
    \vertex [right=of a] (b);
    \vertex [above right=of b] (f1) {\(\nu_{\mu}\)};
    \vertex [below right=of b] (c);
    \vertex [above right=of c] (f2) {\(\overline \nu_{e}\)};
    \vertex [below right=of c] (f3) {\(e^{-}\)};

    \diagram* {
      (a) -- [fermion] (b) -- [fermion] (f1),
      (b) -- [boson, edge label'=\(W^{-}\)] (c),
      (c) -- [anti fermion] (f2),
      (c) -- [fermion] (f3),
    };
  \end{feynman}
\end{tikzpicture} 
\begin{tikzpicture}
  \begin{feynman}
    \vertex (a) {\(\mu^{-}\)};
    \vertex [right=of a] (b);
    \vertex [above right=of b] (f1) {\(\nu_{\mu}\)};
    \vertex [below right=3cm and 3cm of b] (c);
    \path (b) -- (c) coordinate[pos=1/3] (i1) coordinate[pos=2/3] (i2);
    \vertex [above right=of c] (f2) {\(\overline \nu_{e}\)};
    \vertex [below right=of c] (f3) {\(e^{-}\)};

    \diagram* {
      (a) -- [fermion] (b) -- [fermion] (f1),
      (b) -- [boson, edge label'=\(W^{-}\)] (i1),
      (i1) --[fermion,half left] (i2),
      (i2) --[fermion,half left] (i1),
      (i2) -- [boson, edge label'=\(W^{-}\)] (c),
      (c) -- [anti fermion] (f2),
      (c) -- [fermion] (f3),
    };
  \end{feynman}
\end{tikzpicture} 
\end{document}

enter image description here

1
  • Thanks it's working
    – SK Dash
    Oct 12 '19 at 15:26

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