2

I am trying to reproduce the Feynman graph of the Hartree-Fock self energy, composed of two term (exchange and Coulomb), as in the figure:

enter image description here

I have tried the code below, the second term is ok, but I am still half way to get something decent for the first term. How come I am not able to fix points c on the same axis as a-b and c-d on its orthogonal, in the position above?

Can anyone suggest how to put the bubble in the right position and put arrows on it? Any other suggestion is welcomed.

Many thanks

\documentclass{standalone}
\usepackage{tikz-feynman,contour}
\begin{document}
\begin{tikzpicture}
\begin{feynman}
\coordinate (a);
\coordinate[left=1cm of a] (b);
\coordinate[left=1cm of b] (c);
\coordinate[top=1.0cm of c] (d);
\diagram* {
a --[fermion] b[dot];
b --[photon] d;
b --[fermion] c;
};
\end{feynman}
\draw[arc arrow={to pos 0.1 with length 2mm}] (d) arc(0:360:0.5);
\end{tikzpicture}

\begin{tikzpicture}
\begin{feynman}
\coordinate (a);
\coordinate[left=1cm of a] (b);
\coordinate[left=2.0cm of b] (c);
\coordinate[left=4.0cm of a] (d);
\diagram* {
a -- b[dot] -- [photon, half left] c[dot] -- d,
b -- [fermion] c };
\end{feynman}
\end{tikzpicture}


\end{document}

enter image description here

Marco Di Gennaro
  • 193
  • 1
    Can you make a complete example containing all necessary styles? arc arrow isn't a standard style, and I'd also think top should be above. – Torbjørn T. Jul 15 '20 at 18:19

2 Answers2

3

Based on Sebastiano's answer and on this answer, I could get a better, yet not complete, result. enter image description here I had to:

  • compile with lulatex
  • remove the feynman environment from within tikzpicture
  • I defined a photon1/.style={decorate, decoration={snake}, draw=black} style in \tikzset (I tried to modify wave amplitude=0.3mm and wave count=10 but I could not get these equal to the photon style).

I still need to:

  • make the two photons look the same
  • rotate the bubble and align it on top of the photon edge (I now added another point e, probably one can fix it just with the right option on d)
  • add two arrows to the bubble

Below there is the updated version of the code.

Thank you

\documentclass{standalone}

\usepackage{tikz} 
\usetikzlibrary{shapes,arrows,positioning,automata,backgrounds,calc,er,patterns}
\usepackage{tikz-feynman}
\tikzfeynmanset{compat=1.1.0}


% adapted from https://tex.stackexchange.com/a/160358/21344; changed photon style
\tikzset{
  fermion/.style={draw=black, postaction={decorate},decoration={markings,mark=at position .55 with {\arrow{Latex}}}},
  vertex/.style={draw,shape=circle,fill=black,minimum size=2pt,inner sep=0pt},
  photon/.style={wavy semicircle,wave amplitude=0.3mm,wave count=10},
  photon1/.style={decorate, decoration={snake}, draw=black}
}


% adapted from https://tex.stackexchange.com/a/89003/21344; swapped atan args
\newif\ifmirrorsemicircle
\tikzset{
    wave amplitude/.initial=0.2cm,
    wave count/.initial=8,
    mirror semicircle/.is if=mirrorsemicircle,
    mirror semicircle=false,
    wavy semicircle/.style={
        to path={
            let \p1 = (\tikztostart),
            \p2 = (\tikztotarget),
            \n1 = {veclen(\y2-\y1,\x2-\x1)},
            \n2 = {atan2(\x2-\x1,\y2-\y1))} in
            plot [
                smooth,
                samples=(\pgfkeysvalueof{/tikz/wave count}+0.5)8+1, % Calculate the number of samples needed, so the samples are in sync with the wave and fall on the extrema
                domain=0:1,
                shift={($(\p1)!0.5!(\p2)$)}
            ] ({ % Polar coordinates: Angle...
                (\x180-\n2 + 180 + \ifmirrorsemicircle 1 \else -1 \fi * 90%
            }:{ % ... and radius
                (%
                    \n1/2+\pgfkeysvalueof{/tikz/wave amplitude} * %
                    sin(
                        \x * 360 * (\pgfkeysvalueof{/tikz/wave count} + 0.5%
                    )%
                )%
            })
        } (\tikztotarget)
    }
}


\begin{document}


\begin{tikzpicture}
\coordinate (i);
\coordinate[vertex, right=of i] (v1);
\coordinate[vertex, right=of v1] (v2);
\coordinate[right=of v2] (o);
\draw (i) -- (v1);
\draw[fermion] (v1) -- (v2);
\draw[photon] (v1) to (v2);
\draw (v2) -- (o);
\end{tikzpicture}


    

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\begin{tikzpicture}
\coordinate (a);
\coordinate[vertex, right=of a] (b);
\coordinate[vertex, right=of b] (c);
\coordinate[vertex, above=of b] (d);
\coordinate[vertex, above=of d] (e);
\draw [fermion] (a) -- (b);
\draw [fermion] (b) -- (c);
\draw [photon1] (b) to (d);
\draw [arc arrow={to pos 0.0 with length 1mm}] (e) arc(0:360:0.4);
\end{tikzpicture}


\end{document}
Marco Di Gennaro
  • 193
0

This is an half answer: your original drawing has been built with feynMF package. feynMF use METAFONT (or METAPOST).

Here can you see an example to pag. 30 where there is the same loop with the arrows. It is an old package of the 1996.

enter image description here

Now I suggest to see this link: Tikz, decorations or Package for typesetting Feynman diagrams (efficiency of `feynmp` and `tikz`) where it is used for the Feynman diagrams: TikZ-Feynman package.

ADDENDUM: If you prefer to be a flash to draw your image it is possible to use FeynGame a tool in Java for drawing Feynman diagrams only for Linux and MacOS.

Sebastiano
  • 54,118