# How to plot Feynman diagrams with PSTricks

I need to plot some Feynman diagrams for my research papers. Although I had some experience in plotting with PSTricks, it is still not an easy job to plot Feynman diagrams. Could someone provide some tips to make it easier? Many thanks in advance!

• Here you is a good starting point. If you are flexible with choice of package (if you can do it in tikz), here is an example with source code. – Pouya May 25 '13 at 10:16
• You can consider the feynmp package; it's more easily managed with my feynmp-auto that takes care (on a recent TeX Live distribution) of the Metapost runs. – egreg May 25 '13 at 16:18

Remarks

Here is minimal working example using the \pssin command from the pst-coil package and the ArrowInside option from the pstricks-add package.

There is a huge downside with this implementation: You can not preserve the frequency of the sine when shortening the line. The command will always draw as many periods as given in the argument not matter how long the line actually is. Compare: \pssin[periods=5](0,0)(2,0) and \pssin[periods=5](0,0)(8,0).

# Samples

Compile with xelatex.

## 1.)

Inspired by g.kov's answer, I added some labels.

Implementation

\documentclass[border=3mm]{standalone}
\usepackage{pst-coil}
\begin{document}
\psset{arrowscale=2}
\begin{pspicture}(-1.5,-1.5)(4.5,1.5)
% Particles
\psline[ArrowInside=->](-1,-1)(0,0)
\psline[ArrowInside=->](0,0)(-1,1)
\pssin[periods=9,amplitude=0.1,coilarm=0](0,0)(3,0)
\psline[ArrowInside=->](4,-1)(3,0)
\psline[ArrowInside=->](3,0)(4,1)
% Labels
\uput[45](-0.5,0.5){$k'$}
\uput[-45](-0.5,-0.5){$k$}
\uput[135](-1,1){$e^+$}
\uput[225](-1,-1){$e^-$}
\uput[-90](1.5,0){$q$}
\uput[135](3.5,0.5){$q'$}
\uput[225](3.5,-0.5){$q$}
\uput[45](4,1){$\mu^+$}
\uput[-45](4,-1){$\mu^-$}
% Arrows
\psline{->}(-1,0.6)(-0.5,0.1)
\psline{->}(3.5,-0.1)(4,-0.6)
\psline{->}(1,0.3)(2,0.3)
\end{pspicture}
\end{document}


Output

## 2.)

Implementation

\documentclass[border=3mm]{standalone}
\usepackage{pst-coil}
\begin{document}
\psset{arrowscale=2}
\begin{pspicture}(-1,-1)(4,1)
\psline[ArrowInside=->](-1,-1)(0,0)
\psline[ArrowInside=->](0,0)(-1,1)
\pssin[periods=3,amplitude=0.1,coilarm=0](0,0)(1,0)
%No ArrowInside for \psarc :(
\psarc(1.5,0){0.5}{0}{180}\psarc{->}(1.5,0){0.5}{0}{100}
\psarc(1.5,0){0.5}{180}{360}\psarc{->}(1.5,0){0.5}{180}{280}
\pssin[periods=3,amplitude=0.1,coilarm=0](2,0)(3,0)
\psline[ArrowInside=->](4,-1)(3,0)
\psline[ArrowInside=->](3,0)(4,1)
\end{pspicture}
\end{document}


Output

## 3.)

Implementation

As you can see in the screenshot, the \pscoil thing is a little bit tricky.

\documentclass[border=3mm]{standalone}
\usepackage{pst-coil}
\begin{document}
\psset{arrowscale=2}
\begin{pspicture}(0,0)(3,-4)
\psline[ArrowInside=->](0,0)(1,-1)
\psline[ArrowInside=->](2,-1)(3,0)
\pssin[periods=3.5,amplitude=0.1,coilarm=0](1,-1)(2,-1)
\psline[ArrowInside=->](1,-1)(1.5,-2)
\psline[ArrowInside=->](1.5,-2)(2,-1)
\pscoil[coilwidth=0.2,coilarm=0](1.5,-2)(1.5,-3)
\psline[ArrowInside=->](0,-4)(1.5,-3)
\psline[ArrowInside=->](1.5,-3)(3,-4)
\end{pspicture}
\end{document}


Output

• It is cool. I like this implementation. – soliton May 26 '13 at 1:10
• Thanks for your comment. If you like my answer that much, please consider marking it as accepted answer. – Henri Menke May 26 '13 at 9:13
• No ArrowInside for \psellipticarc as well. :-( – Let Me Be Your Lost Disciple Dec 13 '17 at 7:34

There is also an Asymptote module feynman that might be of interest. This is an example demo eetomumu.asy from the distribution:

import feynman;

// set default line width to 0.8bp
currentpen = linewidth(0.8);

// scale all other defaults of the feynman module appropriately
fmdefaults();

// define vertex and external points

real L = 50;

pair zl = (-0.75*L,0);
pair zr = (+0.75*L,0);

pair xu = zl + L*dir(+120);
pair xl = zl + L*dir(-120);

pair yu = zr + L*dir(+60);
pair yl = zr + L*dir(-60);

// draw propagators and vertices

drawFermion(xu--zl);
drawFermion(zl--xl);

drawPhoton(zl--zr);

drawFermion(yu--zr);
drawFermion(zr--yl);

drawVertex(zl);
drawVertex(zr);

// draw momentum arrows and momentum labels

drawMomArrow(xl--zl, Relative(left));
label(Label("$k'$",2RightSide), xl--zl);

label(Label("$k$",2LeftSide), xu--zl);

drawMomArrow(zl--zr, Relative(left));
label(Label("$q$",2RightSide), zl--zr);

drawMomArrow(zr--yu, Relative(right));
label(Label("$p'$",2LeftSide), zr--yu);

label(Label("$p$",2RightSide), zr--yl);

// draw particle labels

label("$e^-$", xu, left);
label("$e^+$", xl, left);

label("$\mu^+$", yu, right);
label("$\mu^-$", yl, right);