I'm trying to draw the Feynman diagram for the following disintegration: Sigma+ -> Lambda0 mu+ mu neutrino

Showing all the quarks, including the two that don't participate, in the same way as this image:

reference disintegration

So far I've managed to get close by using invisible edges to keep lines together, but they are too far away. I've tried using nudge, but as it brings some lines together it also pulls others appart. Also, the W+ boson and its decay products should go in the time direction.

My attempt

MWE (compile with LuaLaTex):

\def \op{0.2} %Opacity of auxiliary lines
    i1 [particle=u]-- [fermion] a -- [fermion] f1 [particle=d],
    i2 [particle=u]-- [fermion] b -- [fermion] f2 [particle=u],
    i3 [particle=s]-- [fermion] c -- [fermion] f3 [particle=s],
    a -- [boson, edge label=\(W^+\)] d,
    d -- [fermion] g1 [particle =\(\mu^+\)],
    d -- [fermion] g2 [particle =\(\nu_\mu\)],
    %Supporting lines
    i1 -- [opacity=\op] i2,
    i2 -- [opacity=\op] i3,
    f1 -- [opacity=\op] f2,
    f2 -- [opacity=\op] f3,
    a  -- [opacity=\op] b,
    b  -- [opacity=\op] c,

1 Answer 1


I just copied the example from p. 28 of the tikz-feynman manual and made a few modifications. Note that this example does not require lualatex, so it can be uploaded to the arXiv and does not suffer from this issue nor this issue.

\vertex (d1) {\(d\)}; 
\vertex[right=5cm of d1] (d2) {\(d\)}; 
\vertex[below=2em of d1] (u1) {\(u\)}; 
\vertex[right=5cm of u1] (u2) {\(u\)};
\vertex[below=2em of u1] (d3) {\(d\)}; 
\vertex[right=5cm of d3] (u3) {\(u\)};
\vertex[below right=1cm and 2.5cm of d3] (v1);
\vertex[below right=1cm and 2cm of v1] (v2);
\vertex[above right=0.5cm and 1cm of v2] (nu) {$\bar\nu_e$};
\vertex[below right=0.5cm and 1cm of v2] (e) {$e^-$};
\diagram* { {[edges=fermion]
(d1) -- (d2),  (u1) -- (u2),
(d3) -- (v1) -- (u3), (nu) -- (v2) -- (e)},
(v1) -- [boson, edge label=\(W\)] (v2)
\draw [decoration={brace}, decorate] (d3.south west) -- (d1.north west) node [pos=0.5, left] {\(n\)};
\draw [decoration={brace}, decorate] (d2.north east) --  (u3.south east) node [pos=0.5, right] {\(p\)};

enter image description here

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .