4

This is what I got. Here is an example. Can you help me with the second one? I am able to do all but not the cross in the center.

image showing what should be drawn as Feynman diagram

$0\nu\beta\beta$ 


\usepackage{feynmp}

\usepackage{ifpdf}
\ifpdf
  \DeclareGraphicsRule{*}{mps}{*}{}
\fi

\makeatletter
\def\endfmffile{%
  \fmfcmd{\p@rcent\space the end.^^J%
          end.^^J%
          endinput;}%
  \if@fmfio
    \immediate\closeout\@outfmf
  \fi 
  \IfFileExists{\thefmffile.mp}{\immediate\write18{mpost \thefmffile}}{}
  \let\thefmffile\relax
}
\makeatother

\begin{fmffile}{0nu2beta}
\begin{fmfgraph}(200,150)
\fmfpen{thick}
\fmfleft{i1,i4} 
\fmfright{o1,o2,o3,o4}
\fmf{fermion,tension=1}{i1,v1}
\fmf{fermion,tension=0.5}{v1,o1}
\fmf{fermion,tension=1}{i4,v4}
\fmf{fermion,tension=0.5}{v4,o4}
\fmf{fermion,tension=.35}{v2,o2}
\fmf{fermion,tension=.35}{v3,o3}
\fmf{fermion,tension=0.20}{v2,v3}
\fmf{fermion,tension=0.20}{v3,v2}
%\fmf{crossed}{v2,v3}
\fmf{photon,tension=0.5}{v1,v2}
\fmf{photon,tension=0.5}{v4,v3}
\fmfdot{v1,v2,v3,v4}
\end{fmfgraph} 
\end{fmffile}'

crossed is not working

(P.S. I know I am not using this copied code but cross should work and its not working with \fmf{crossed}{v2,v3} why? and how to solve it?

\fmfcmd{%
style_def majorana expr p =
cdraw p;
cfill (harrow (reverse p, .5));
cfill (harrow (p, .5))
enddef;
style_def alt_majorana expr p =
cdraw p;
cfill (tarrow (reverse p, .55));
cfill (tarrow (p, .55))
enddef;})
3
  • Welcome! Show us what you've done! The best way to do that is to provide a minimal document that we can compile, a MWE.
    – Clément
    Feb 15 '16 at 20:09
  • Please be aware that not everybody is familiar with particle physics! (A majorana particle is a fermion that is its own anti-particle)
    – user31729
    Feb 15 '16 at 20:15
  • 1
    With so little in the way of information, I would suggest you look at this link and see if it solves your issue. If so, let us know. tex.stackexchange.com/questions/86588/… Feb 15 '16 at 20:16
4

Instead of feynmp, there is a new package called tikz-feynman (project page) which also allows you to draw Feynman diagram. In particular, it has support for Majorana particles and mass insertions:

\documentclass[convert]{standalone}

\usepackage[compat=1.1.0]{tikz-feynman}

\begin{document}
\begin{tikzpicture}
  \begin{feynman}
    \vertex (b);
    \vertex [below=of b] (c);
    \vertex [below left=1cm and 0.4cm of c] (d);
    \vertex [above left=1cm and 0.4cm of b] (a);
    \vertex [left=of a] (i1);
    \vertex [left=of d] (i2);
    \vertex[above right of=a] (f1);
    \vertex[right of=b] (f2);
    \vertex[right of=c] (f3);
    \vertex[below right of=d] (f4);

    \diagram* {
      (a) -- [photon] (b) -- [majorana, insertion=0.5] (c) -- [photon] (d),
      (i1) -- [fermion] (a),
      (i2) -- [fermion] (d),
      (a) -- [fermion] (f1),
      (b) -- [fermion] (f2),
      (c) -- [fermion] (f3),
      (d) -- [fermion] (f4),
    };
  \end{feynman}
\end{tikzpicture}
\end{document}

output

3

enter image description hereI just paste the code for feynmp.

\begin{fmfgraph*}(50,50)
\fmfleft{i0,i1,i2,i3}
\fmfright{f0,f1,f2,f3}
\fmf{fermion,label=$n$,label.side=right}{i3,v1}
\fmf{fermion,label=$p$,label.side=right}{v1,f3}
\fmf{boson,label=$W$,label.side=right,tension=0.3}{v1,v2}
\fmf{fermion,label=$e^-$,label.side=right}{v2,f2}
\fmf{phantom}{i2,v2}
\fmf{plain}{v2,v3,v4}
\fmf{phantom}{i1,v4}
\fmf{fermion,label=$e^-$,label.side=right}{v4,f1}
\fmf{boson,label=$W$,label.side=right,tension=0.3}{v4,v5}
\fmf{fermion,label=$n$,label.side=right}{i0,v5}
\fmf{fermion,label=$p$,label.side=right}{v5,f0}
\fmfdot{v1,v2,v4,v5}
\fmfv{decor.shape=cross,decor.size=.1w}{v3}
\end{fmfgraph*}
1

I added a cross on a dummy vertex and now the code for neutrinoless double beta decay is: [P.S. Use Astrek (with fmfgraphs) to use labels!]

    \documentclass[paper=a4, fontsize=11pt]{article}
    \usepackage{feynmp}
    %\usepackage{feynmf}
    \usepackage{ifpdf}
    \ifpdf
      \DeclareGraphicsRule{*}{mps}{*}{}
    \fi
    \makeatletter
    \def\endfmffile{%
      \fmfcmd{\p@rcent\space the end.^^J%
              end.^^J%
              endinput;}%
      \if@fmfio
        \immediate\closeout\@outfmf
      \fi
      \IfFileExists{\thefmffile.mp}{\immediate\write18{mpost \thefmffile}}{}
      \let\thefmffile\relax
    }
    \makeatother
    \begin{document}
    \begin{center}
    \begin{fmffile}{0nu2beta}
    \begin{fmfgraph*}(200,200)
    %\fmfpen{thick}
    \fmfleft{i1,i4} 
    \fmfright{o1,o2,o3,o4}
    \fmf{fermion,tension=.8}{i1,v1}
    \fmf{fermion,tension=0.5}{v1,o1}
    \fmf{fermion,tension=.8}{i4,v4}
    \fmf{fermion,tension=0.5}{v4,o4}
    \fmf{fermion,tension=.4}{v2,o2}
    \fmf{fermion,tension=.4}{v3,o3}
    \fmf{fermion,tension=1}{v5,v2}
    \fmf{fermion,tension=1}{v5,v3}
    \fmfv{decor.shape=cross}{v5} % This is the point where I used cross on a dummy vertex
    \fmf{photon,tension=.65,label=$W_L$}{v1,v2}
    \fmf{photon,tension=.65,label=$W_L$}{v4,v3}
    %\fmf{phantom, tension=2}{o1,o2,o3,o4,i1}
    \fmfdot{v1,v2,v3,v4}
    \fmflabel{$v_1$}{v5}
    \fmflabel{u}{o1}
    \fmflabel{$e_L$}{o2}
    \fmflabel{$e_L$}{o3}
    \fmflabel{u}{o4}
    \fmflabel{d}{i1}
    \fmflabel{d}{i4}
    \end{fmfgraph*} 
    \end{fmffile}

    \end{center} 
    \end {document}

There is an interesting link I found to help you with Feynman Diagrams: Blog for installing feynmf and feynmp packages to Miktex (with some good ref. for using these packages too)!

This particular PDF is very useful to just understand above package for minimal use in Particle Physics. Enjoy!

1
  • Are you aware that feynmp-auto package avoids you 99% of your preamble?
    – giordano
    Feb 15 '16 at 23:14

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