# Making a feynman diagram of W boson production in pp collisions

I'm trying to create a Feynman diagram where a proton and antiproton collide and 2 of their partons create a W boson which then decays leptonically. I made an attempt using the following code:

\feynmandiagram [horizontal=a to b] {
p1 [particle=$$\overline{p}$$, opacity=0] -- [anti fermion] b1 [blob] -- [anti fermion, edge label = $$\overline{u}$$] a,
p2 [particle=$$p$$] -- [fermion] b2 [blob] -- [fermion, edge label = $$u$$] a,
a -- [boson, edge label=$$W^{+}$$] b,
f1 [particle=$$e^{+}$$] -- [fermion] b -- [fermion] f2 [particle=$$\nu_{e}$$],
p1 -- [opacity=0] p2,

b1 -- [anti fermion] r11,
b1 -- [anti fermion] r12,
r11 -- [fermion, opacity=0] b,
r12 -- [fermion, opacity=0] b,

b2 -- [fermion] r21,
b2 -- [fermion] r22,
r21 -- [fermion, opacity=0] b,
r22 -- [fermion, opacity=0] b,
};


However, this doesn't look very nice. First of all, I would like to get both of the incoming protons on the left to have horizontal lines. Secondly, if possible, I would also like the 2 quarks that don't partake in the W production to be horizontal as well (or at least parallel) and equal in length.

I also used some opacity=0 connections to get everything roughly in the correct place. Without these, the diagram looks even less like what I have in mind, but I think it's probably not the way to go since this doesn't result in a nice diagram. How could I solve this using tikz-feynman with compat=1.1.0?

EDIT: Adding a drawing of what i have in mind roughly:

EDIT 2: I just noticed that in my latex diagram, there is an up and anti up quark instead of down and anti up, you can ignore that. There's also a mistake with my quark in my own diagram, oops.

By using a different way of constructing the diagram, which uses manually placed vertices, I managed to get something that looks like what I was aiming for. It's not a very pretty solution but it does the job (compiled with LuaLaTeX):

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

\begin{document}
\begin{tikzpicture}
\begin{feynman}
\vertex[blob] (b1) at (0, 0) {};
\vertex[blob] (b2) at (0,-3) {};

\vertex (w1) at (1,-1.5);
\vertex[right = of w1] (w2);

\vertex[left = of b1] (p1) {$p$};
\vertex[left = of b2] (p2) {$\overline{p}$};

\vertex[above right=of w2] (l1) {$\nu_{e} / \nu_{\mu}$};
\vertex[below right=of w2] (l2) {$e^{+} / \mu^{+}$};

\vertex (b11) at (0.35, 0.15);
\vertex (b12) at (0.35, -0.15);
\vertex (r11) at (1.5, 0.15);
\vertex (r12) at (1.5, -0.15);

\vertex (b21) at (0.35, -3 + 0.15);
\vertex (b22) at (0.35, -3 - 0.15);
\vertex (r21) at (1.5, -3 + 0.15);
\vertex (r22) at (1.5, -3 - 0.15);

\diagram* {
(p1) -- [fermion] (b1) -- [fermion, edge label = $$d$$] (w1),
(p2) -- [anti fermion] (b2) -- [anti fermion, edge label' = $$\overline{u}$$] (w1),

(w1) -- [boson, edge label = $$W^{+}$$] (w2),
(l2) -- [fermion] (w2) -- [fermion] (l1),

(b11) -- [fermion] (r11),
(b12) -- [fermion] (r12),
(b21) -- [anti fermion] (r21),
(b22) -- [anti fermion] (r22),
};
\end{feynman}
\end{tikzpicture}

\end{document}


If there are any other suggestions that might be more elegant, you're always welcome to comment them.

• What is your minimal working example, please? I see only a fragment. Commented Apr 7, 2023 at 12:00
• You're right, I forgot to add the \documentclass{}, \usepackage{} and \begin{document} and \end{document} commands. They've now been added, so it should be compilable now. Commented Apr 7, 2023 at 13:21
• What is the font used? No Computer moderm I think. Commented Apr 7, 2023 at 18:23
• It is Arial, because I was using this in a template, but apart from the font, nothing should change if you compile it without any template. Commented Apr 7, 2023 at 21:15