I'm having a bit too much horizontal space in this MWE, and want a normal spacing:
\documentclass[11pt,letterpaper,twoside]{book}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage[total={6in,10in},left=1.5in,top=0.5in,includehead,includefoot]{geometry}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{mathtools}
\begin{document}
\begin{subequations}
\begin{alignat}{2}
\phi \quad &\Rightarrow \quad \tilde{\phi} &&= e^{-\, i q \vartheta} \, \phi, \\[1ex]
A_{\mu} \quad &\Rightarrow \quad \tilde{A}_{\mu} &&= A_{\mu} + \partial_{\mu} \, \vartheta,
\end{alignat}
\end{subequations}
\end{document}
Here's a preview of the problem, shown in red:
I need the arrows and the equal signs to be aligned, and I want the same normal space on each sides of these symbols. Currently, there's too much space after the \phi
symbol. How can I fix that without hacking (i.e. without adding phantom tricks)?