%% luatex85 is only necesary to fix a bug in standalone
RequirePackage{luatex85}
documentclass{standalone}

usepackage[compat=1.1.0]{tikz-feynman}

begin{document}
feynmandiagram [horizontal=a to b, layered layout] {
  a -- b [dot] -- [out=135, in=45, loop, min distance=3cm] b -- c,
};
end{document}