6

I am new to LaTeX, and have been trying to find a way to draw Feynman diagrams involving SUSY particles, i.e gauginos and superpartner scalars. I am wondering if there is any way to use the feynmf package to achieve this, or if there perhaps exists another package for this purpose. The gaugino I am trying to make, for example, looks like the line coming in from the lower left in the diagram below.

gaugino

  • 2
    If you can find a paper on the arxiv that has the diagrams you want, click on its arXiv number and then click on "other formats" and then click on "source". You get the original tex file (assuming it was written in tex, which is a pretty safe assumption). Then you search the tex file to see how the authors typeset their diagrams. – Benjamin McKay Sep 24 '15 at 17:57
  • 2
    Have a look at this site. There's a package there that adds supersymmetry particles to feynmf. – Thruston Sep 24 '15 at 18:21
  • Nice idea @BenjaminMcKay. I'll give that a try. – Nick Murphy Sep 24 '15 at 18:25
  • @Thurston A gaugino, for example, just looks like a combined fermion-photon line, essentially a wiggly superimposed on a fermion line. – Nick Murphy Sep 24 '15 at 18:26
  • 2
    Can you add to your question an image of the kind of diagram you want to achieve? I have no idea what a gaugino or a superpartner scalar is, but once I see them, I could suggest you what to do. – Gonzalo Medina Sep 24 '15 at 22:43
7

I created a package called TikZ-Feynman which is available from CTAN, and in today's update, I have added support for SUSY particles by allowing edge styles to be stacked.

Here's the code for the above diagram

\documentclass[tikz]{standalone}
\usepackage[compat=1.1.0]{tikz-feynman}
\begin{document}
\feynmandiagram [large, horizontal=a to b] {
  i1 [particle=\(\langle H_{u} \rangle\)] 
     -- [scalar, with reversed arrow=0.3, insertion=0.7, edge label=\(H_{2}\)] a
     -- [anti fermion, boson]
     i2 [particle=\(\lambda\)],
  a -- [anti majorana, insertion=0.5, edge label={\(\tilde H_{2}\quad\tilde H_{1}\)}] b,
  f1 [particle=\(\tilde f\)]
     -- [charged scalar] b
     -- [anti fermion]
     f2 [particle=\(f'\)],
};
\end{document}

and the corresponding output:

SUSY diagram

Note that the lines are fairly thick here because of the large style being used.

1

It is possible and relatively easy in Feynmf. The simplest way is to actually draw the line twice with the two different styles to combine. The only complication is to ensure that the SUSY line isn't pulled too short. There are two ways to avoid this. First is to use \fmffreeze before drawing the second style for the line as this freezes the layout before applying the line and therefore it can't affect the layout. The second is to use tension of 0.5 to fix the total line tension to be correct.

My code is here:

\begin{fmfgraph*}(300,150)
  \fmfleft{i1,i2}
  \fmfright{o1,o2}
  \fmf{fermion}{i1,v1}
  \fmf{scalar}{o2,v3}
  \fmf{fermion,tension=2,label=$\tilde{H}_2$}{v2,v1}
  \fmf{fermion,tension=2,label=$\tilde{H}_1$}{v2,v3}
  \fmf{scalar,tension=2,label=$H_2$}{v1,vx}
  \fmf{scalar,tension=2}{vx,i2}
  \fmf{fermion}{o1,v3}
  \fmffreeze
  \fmf{boson}{i1,v1}
  \fmfv{d.sh=cross,label=$M$}{v2}
  \fmfv{d.sh=cross,d.an=45,label=$M_{\mu_1}$}{vx}
  \fmfv{label=$\lambda$}{i1}
  \fmfv{label=$\left<H_u\right>$}{i2}
  \fmfv{label=$f'$}{o1}
  \fmfv{label=$\tilde f$}{o2}
\end{fmfgraph*}

The output is Feynman Diagram

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.