[Tex/LaTex] Tikz-Feynman: Multiple arrows on one fermion line and alignment (0vββ)

arrowshorizontal alignmenttikz-feynman

I'm trying to align the quark arrows in my 0vββ diagram:

So I'd like to have 2 arrows on each of the 4 'unmodified' quark lines: the first arrow should be horizontally aligned with the arrow from the interacting down quark (such that it is directly above the d quark arrow). Same for the 2nd arrow, it should be directly above the arrow of the outgoing up quark.

Basically like in the left diagram here:

So my question is

1) How do I get 2 arrows on one fermion line

2) How can the arrows be aligned correctly?

( 3) And by the way, is it possible to move the Majorana neutrino label a little bit more to the left?)

Didn't find anything in the manual.

This is my code:

\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 1.4cm of c] (d);
\vertex [above left=1cm and 1.4cm of b] (a);
\vertex [left=of a] (i1) {d};
\vertex [left=of d] (i2) {d};
\vertex[right = 2cm of b] (f2) { \(e^{-}\)};
\vertex[right = 2cm of c] (f3) { \(e^{-}\)};
\vertex[below = 2cm of f3] (f4) {u};

\vertex[above = 2cm of f2] (f1) {u};

\vertex[above=0.35cm of i1] (f6) {d}; % d quark outgoing
\vertex[above=0.35cm of f1] (i3) {d}; % d quark ingoing

\vertex[above=0.35cm of i3] (f7) {u}; % u quark outgoing
\vertex[above=0.35cm of f6] (i4) {u}; % u quark ingoing

% copy quarks for bottom

\vertex[below=0.35cm of i2] (f8) {d}; % d quark outgoing
\vertex[below=0.35cm of f4] (i5) {d}; % d quark ingoing

\vertex[below=0.35cm of i5] (f9) {u}; % u quark outgoing
\vertex[below=0.35cm of f8] (i6) {u}; % u quark ingoing


\diagram* {
    (a) -- [boson, edge label'=\(W^{-}\)] (b) -- [anti majorana, insertion=0.5, edge label' = \(\nu_{M}\) ] (c) -- [boson, edge label'=\(W^{-}\)] (d),
    (i1) -- [fermion] (a),
    (i2) -- [fermion] (d),
    (a) -- [fermion] (f1),
    (b) -- [fermion] (f2),
    (c) -- [fermion] (f3),
    (d) -- [fermion] (f4),
    (f6) -- [fermion, out=0, in=200] (i3),
    (i4) -- [fermion, out=0, in=200] (f7),
    (f8) -- [fermion, out=0, in=160] (i5),
    (i6) -- [fermion, out=0, in=160] (f9),
};

\draw [decoration = {brace} , decorate] (i1.south west) -- (i4.north west) node [pos = 0.5 , left = 0.125cm] {\huge n};

\draw [decoration = {brace} , decorate] (f7.north east) -- (f1.south east) node [pos = 0.5 , right = 0.125cm] {\huge p};

\draw [decoration = {brace} , decorate] (i6.south west) -- (i2.north west) node [pos = 0.5 , left = 0.125cm] {\huge n};

\draw [decoration = {brace} , decorate] (f4.north east) -- (f9.south east) node [pos = 0.5 , right = 0.125cm] {\huge p};

\end{feynman}
\end{tikzpicture}
\end{document}

Thank you very much! 🙂

Best Answer

The fermion, Majorana and charged boson styles actually all use an internal (and undocumented) with arrow style. I didn't make the with arrow style public because I didn't initially envisage it being needed though I think I will be making it public in the next version of TikZ-Feynman.

The with arrow and with reversed arrow styles place an arrow or reversed arrow along the path at the given position. The position can be specified in of the following:

A number in between 0 and 1: This tells what how far down the path to place the arrow such that 0 corresponds to the start, 0.5 is the halfway point, and 1 is the end;
A positive distance: the arrow is placed at the given distance down the path;
A negative distance: the arrow is placed at the given distance from the end of the path.

Since in your case, we want the arrows to be aligned, I actually defined two temporary commands to hold the distance, \tmpda and \tmpdb, and use these as the arguments to with arrow. This avoids having to manually adjust each distance.

\documentclass[tikz]{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 1.4cm of c] (d);
    \vertex [above left=1cm and 1.4cm of b] (a);
    \vertex [left=of a] (i1) {d};
    \vertex [left=of d] (i2) {d};
    \vertex [right = 2cm of b] (f2) {\(e^{-}\)};
    \vertex [right = 2cm of c] (f3) {\(e^{-}\)};
    \vertex [below = 2cm of f3] (f4) {u};

    \vertex [above = 2cm of f2] (f1) {u};

    \vertex [above=0.35cm of i1] (f6) {d}; % d quark outgoing
    \vertex [above=0.35cm of f1] (i3) {d}; % d quark ingoing

    \vertex [above=0.35cm of i3] (f7) {u}; % u quark outgoing
    \vertex [above=0.35cm of f6] (i4) {u}; % u quark ingoing

    % copy quarks for bottom

    \vertex [below=0.35cm of i2] (f8) {d}; % d quark outgoing
    \vertex [below=0.35cm of f4] (i5) {d}; % d quark ingoing

    \vertex [below=0.35cm of i5] (f9) {u}; % u quark outgoing
    \vertex [below=0.35cm of f8] (i6) {u}; % u quark ingoing

    \newcommand\tmpda{0.7cm}
    \newcommand\tmpdb{-1.7cm}
    \diagram* {
      (a) -- [boson, edge label'=\(W^{-}\)] (b) -- [anti majorana, insertion=0.5, edge label' = \(\nu_{M}\) ] (c) -- [boson, edge label'=\(W^{-}\)] (d),
      (i1) -- [with arrow=\tmpda] (a),
      (i2) -- [with arrow=\tmpda] (d),
      (a) -- [with arrow=\tmpdb] (f1),
      (b) -- [fermion] (f2),
      (c) -- [fermion] (f3),
      (d) -- [with arrow=\tmpdb] (f4),
      (f6) -- [with arrow=\tmpda, with arrow=\tmpdb, out=0, in=200] (i3),
      (i4) -- [with arrow=\tmpda, with arrow=\tmpdb, out=0, in=200] (f7),
      (f8) -- [with arrow=\tmpda, with arrow=\tmpdb, out=0, in=160] (i5),
      (i6) -- [with arrow=\tmpda, with arrow=\tmpdb, out=0, in=160] (f9),
    };

    \draw [decoration = {brace} , decorate] (i1.south west) -- (i4.north west) node [pos = 0.5 , left = 0.125cm] {\huge n};

    \draw [decoration = {brace} , decorate] (f7.north east) -- (f1.south east) node [pos = 0.5 , right = 0.125cm] {\huge p};

    \draw [decoration = {brace} , decorate] (i6.south west) -- (i2.north west) node [pos = 0.5 , left = 0.125cm] {\huge n};

    \draw [decoration = {brace} , decorate] (f4.north east) -- (f9.south east) node [pos = 0.5 , right = 0.125cm] {\huge p};

  \end{feynman}
\end{tikzpicture}
\end{document}

I hope that helps! Also, very nice diagram! It's good seeing TikZ-Feynman being used :)

Related Solutions

[Tex/LaTex] How to have one straight arrows surrounded by two curved arrows (TikZ)

you can create a node at each end of the lines and then connect these nodes. by adjusting the minimum size of node you can improve aesthetics.

(sorry for my google english)


\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{arrows,decorations.pathmorphing,backgrounds,positioning,fit,petri,calc,shadows}

\begin{document}

\begin{tikzpicture}[
    parent/.style={%
        rounded corners,
        thick,
        draw=red!75,
        fill=red!20,
        thick,
        inner ysep=2pt,
        inner xsep=2pt,
        minimum width = 4cm,
        minimum height = 1.5cm,
        align=center
    },
    child/.style={%
        rounded corners,
        thick,
        draw=blue!90,
        fill=blue!35,
        thick,
        inner ysep=2pt,
        inner xsep=2pt,
        minimum width = 4cm,
        minimum height = 1.5cm,
        align=center
    },
    grandchild/.style={%
        rounded corners,
        thick,
        draw=green!90,
        fill=green!35,
        thick,
        inner ysep=2pt,
        inner xsep=2pt,
        minimum width = 4cm,
        minimum height = 1.5cm,
        align=center
    },
    line/.style={%
        semithick,
        ->,
        shorten >=1pt,
        >=stealth'
    },
    call/.style={%
        blue,
        semithick,
        ->,
        shorten >=1pt,
        >=stealth'
    },
    return/.style={%
        red,
        semithick,
        ->,
        shorten >=1pt,
        >=stealth'
    }]
    \node[child] (child) {Child};
    \node[parent] at (-6,3) (parent 1) {Node 1\\I have manually\\connected this one};
    \node[parent] at (0,3) (parent 2) {Node 2\\I have manually\\connected this one};
    \node[parent] at (6,3) (parent 3) {Node 3\\I have manually\\connected this one};
    \node[parent] at (-6,-3) (grandchild 1) {Node 4\\I have manually\\connected this one};
    \node[parent] at (0,-3) (grandchild 2) {Node 5\\I have NOT manually\\connacted this one};
    \node[parent] at (6,-3) (grandchild 3) {Node 6\\I have NOT manually\\connacted this one};

    %draw three lines from each parent to each child
    \draw [line] (parent 1.south east)node[above left](p1){} -- (child.north west)node[below right](c1){};
    \draw [line] (parent 2.south)node[above](p2){} -- (child.north)node[below](c2){};
    \draw [line] (parent 3.south west)node[above right](p3){} -- (child.north east) node[below left](c3){};

    %draw three lines from each parent to each child
    \draw [line] (grandchild 1.north east)node[below left,minimum size=2em](p4){} -- (child.south west)node[above right,minimum size=2em](c4){};
    \draw [line] (grandchild 2.north)node[below,minimum size=2em](p5){} -- (child.south)node[above,minimum size=2em](c5){};
    \draw [line] (grandchild 3.north west)node[below right](p6){} -- (child.south east)node[above left](c6){};


\foreach \nn in{1,2,3,4,5,6}{
    \draw [call] (p\nn) to [bend right=15] (c\nn);
    \draw [return] (c\nn) to [bend right=15] (p\nn);
    }

\end{tikzpicture}

\end{document}!

the result

[Tex/LaTex] TikZ-Feynman: layers and alignment

Good to see TikZ-Feynman being put to good use!

So, the main issue here is that the layered layout (unlike most other algorithms) takes into account the order in which vertices are specified. In particular, it has a notion of layers and with:

a -- b

This tells it that a is on the layer above b and is distinct from b -- a. So in your example, you have

g [particle=\(\nu\)] 
  -- f 
  -- h [particle=\(\bar{\nu}\)]

and as a result, the neutrino at g is on the layer above f which itself is a layer above the antineutrino at h, hence why the neutrino is awkwardly sitting at the bottom of the central fermion line.

Now as to make it more compact, you can use sibling distance and layer distance to adjust the separation between vertices on the same layer or across layers respectively.

With all this, two of the three dot-points above are addressed:

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

 \begin{document}

 \feynmandiagram[layered layout, vertical=a to c, sibling distance=1cm] {
   g1 [particle=\(g\)]
     -- [gluon] a
     -- [fermion] t1 [particle=\(t\)],
  { [same layer]
    c -- [fermion, edge label=\(t\)] b
      -- [fermion, edge label=\(t\)] a},
   b  -- [boson, edge label=\(Z\)] n2,
   n2 -- [anti fermion] n1 [particle=\(\overline \nu\)],
   n2 -- [fermion] n3 [particle=\(\nu\)],
   g2 [particle=\(g\)]
      -- [gluon] c
      -- [anti fermion] t2 [particle=\(\overline t\)],
 };
\end{document}

Finally, if you want even finer control on everything, then the algorithm won't be able to meet all your needs and you'll have to adjust things manually. You can see some example of this being done at:

How to draw Feynman diagram for Majorana particles?

Tikz-Feynman: Multiple arrows on one fermion line and alignment (0vββ)

Best Answer

Related Solutions

[Tex/LaTex] How to have one straight arrows surrounded by two curved arrows (TikZ)

[Tex/LaTex] TikZ-Feynman: layers and alignment

Related Question