Feynman diagram with TikZ-Feynman

[Gaussian97]

TL;DR

How can I write a loop in $\phi^4$ theory with TikZ-Feynman?

Hi, I'm learning how to draw Feynman diagrams in LaTeX using the TikZ-Feynman package, but in https://arxiv.org/ftp/arxiv/papers/1601/1601.05437.pdf I don't see if it's possible to draw loops in $\lambda \phi^4$ theory, how can I draw a loop that goes from one vertex to itself?

Thanks

 

[sysprog]

https://tex.stackexchange.com/questions/49149/self-loop-in-an-undirected-graph-using-tikz

 

[Gaussian97]

Well, it's ok but it's not what I was looking.
By now I can create a loop, for example with the code

\begin{tikzpicture}
  \tikzfeynmanset{
  every vertex = {dot}
  }
  \begin{feynman}[small]
    \vertex (a1) {};
    \vertex[right=1.5cm of a1] (a2);
    \vertex[right=1.5cm of a2] (a3) {};
    \vertex[above=0.6cm of a2] (b);

    \diagram* {
      (a1) --[scalar] (a2) --[half left] (b) --[half left] (a2) --[scalar] (a3),
    };
    \path (b)--++(90:0.3) coordinate (A);
    \draw (A) circle(0.3);
  \end{feynman}
\end{tikzpicture}

I draw

But I wonder if there is a better way to do it.

 

[sysprog]

The node-to-node closed circuits don't have to be radially circular, but what's been presented here to you is not inconsistent with what apparently you asked for -- analogously, just as $\TeX$ requires you to be very specific in your commands, we need you to be very specific in saying what you're seeking, if we're to be optimally helpfully or assistively responsive.

 

[Gaussian97]

Yes, I know they don't have to be, it's not this what matters, I did it circular because I like it.
Sorry for the ambiguous question, my question is, can I do the same I did but without doing this \path and \draw, only with the TikZ-Feynman commands?
Something like adding (b) --[loop] (b)

Thanks for your time.

 

[sysprog]

Yes, I know they don't have to be, it's not this what matters, I did it circular because I like it.
Sorry for the ambiguous question, my question is, can I do the same I did but without doing this \path and \draw, only with the TikZ-Feynman commands?
Something like adding (b) --[loop] (b)

Thanks for your time.

I don't see why you're reluctant to use \path and \draw, and furthermore, if you're interested in more sophisticated than usual $\LaTeX$ graphics, I suggest that you might see how SVG can be brought in -- maybe have a look at https://wiki.inkscape.org/wiki/index.php/LaTeX

 

[sysprog]

Here's a TikZ-Feynman reference: https://arxiv.org/ftp/arxiv/papers/1601/1601.05437.pdf

 

[JD_PM]

Hi!

I am aimed to learn how to draw Feynman Diagrams using $\TeX$ from scratch and I am looking for some advice

The document shared by @Gaussian97 really helps. I am trying to reproduce the first of the diagrams (section 2.2, A First Diagram).

I naively followed the following steps:

1) Adding the package \usepackage{tikz-feynman} and \tikzfeynmanset{compat=1.0.0} as a warning.

2) Then I simply copy-pasted the code for the first of the diagrams

\feynmandiagram[horizontal=a to b] {
    i1 -- [fermion] a -- [fermion] i2,
    a -- [photon] b,
    f1 -- [fermion] b -- [fermion] f2,
};

But the output was

Instead of the beautiful looking

What am I missing?

Any advice is very welcomed.

Thank you!

 

[Gaussian97]

Hello @JD_PM, I'm not an expert at all in this kind of things but I had the same problem the first time I tried to use tikz-feynman, I don't know if this will work for you but I'll tell you how I fix it (if it doesn't work then I have no idea).

In my case, the problem is that I was using the PDFLaTeX compiler (which was the default option), but to use some functionalities of tikz-feynman you must use the LuaLaTeX compiler.

Here's how I discovered the problem and how I fixed it (in case it helps you)

In my case, I use TexMaker as the editor to write LaTeX documents. In it, you can look at the log and usually it gives a message when something is wrong (In any case, look if you have some document named "Name_of_the_document.log" and open it with the notepad), I got the following message:

Package tikz-feynman Warning: LuaTeX is required if you wish to have vertices automatically placed. You can disable this warning by setting /tikzfeynman/warn luatex=false on input line 50.

Then I found that, in fact, the first line of the log was

This is pdfTeX, Version 3.14159265-2.6-1.40.21 (MiKTeX 20.7) (preloaded format=pdflatex 2020.8.21)

And found that, when I click the Run button (that for me was some kind of magic that make appear a pdf with the things I wrote) it was really doing two things: PdfLaTeX + View PDF (which I assume are some kind of commands)

After looking into the options of the editor I finally found that there was the option of compiling using LuaLaTeX, and after doing that (and the View PDF) i finally got the diagram correctly and my log file start with

This is LuaHBTeX, Version 1.12.0 (MiKTeX 20.7) (format=lualatex 2020.8.22)

and there was no Package tikz-feynman Warning

Hope it helps you