Consider the following code:
\documentclass{article}
\usepackage{tikz}
\usepackage{tikz-feynman}
\begin{document}
$$\begin{tikzpicture}[scale=0.5, baseline=(current bounding box.center)]
\begin{feynman}
\vertex (x);
\vertex[right=of x] (y);
\vertex[above left=of x] (a);
\vertex[below left=of x] (b);
\vertex[above right=of y] (c);
\vertex[below right=of y] (d);
\diagram*{
(x) --[fermion, half left] (y),
(x) --[anti fermion, half right] (y),
(a) --[charged scalar] (x),
(x) --[charged scalar] (b),
(y) --[anti fermion] (c),
(y) --[fermion] (d),
};
\end{feynman}
\end{tikzpicture}$$
\end{document}
Although I put scale=0.5
option in the tikzpicture environment, it seems that the scaling does not work. How can I fix this problem?
scale=0.5
only affects the coordinates. Tryscale=0.5, transform shape
... (and by the way, do not use $$: tex.stackexchange.com/questions/503/why-is-preferable-to)