I have a Feynman diagram like this:

I want to add to it some lines joining the final states, in a way a bit like this (drawn using TikZ):

How could this be done (preferably using feynMP)? How could the lines be made to contact the end points of the final state lines? How could the lines be made to approach but not actually contact the end points of the final state lines?

feynMP code:



\unitlength=1.00 mm






\fmf{curly, label=\(g\)}{v3,v4}




TikZ code:



\unitlength=0.70 mm
  • If you can explain what you need in non-discipline-specific terms, you will have a larger pool of potential helpers. To me, for example, your question is currently rather unclear.
    – cfr
    Sep 13, 2016 at 23:24
  • @cfr, short introduction to Feynman diagrams: Something comes in (g & g on the left), and something goes out (t, b, bbar & tbar on the right). The lines say that something is happening, the curly and straight lines are for different interactions. PO wants to inter-connect all particles on the right, showing that there is a relation between them. Sep 14, 2016 at 5:55
  • @cfr: That is a gluon-gluon fusion process which produces some top- and bottom-quarks. Stuff like this happens in high-energy particle accelerators like the LHC — in case you need some keywords to google for ;) Sep 14, 2016 at 6:00
  • 1
    If you're fine working with TikZ you should definitely check out tikz-feynman package: jpellis.me/projects/tikz-feynman
    – giordano
    Sep 14, 2016 at 11:10
  • Thanks @ralfix I was more thinking that some indication of which are the 'final state lines' would be helpful ;).
    – cfr
    Sep 14, 2016 at 12:27

1 Answer 1


You could use \fmf{...}{...}, just like you did for the other connections, with the double line style. Adding


results in

feynman diagram

  • Thanks very much for your solution to that. It works well. Would you happen to know if it is possible for the lines to end a bit before their vertex?
    – d3pd
    Sep 14, 2016 at 10:27
  • Sorry @d3pd, I can't think of a way to do that with feynmp. You could give tikz-feynman a try, as giordano suggested, but I never used that one. Sep 15, 2016 at 11:28

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