In this context document
\starttext
$T(t)\quad \hat{T}(t)$
\stoptext
the spacing after "\hat T" and (t) is smaller then after the "T"
without accent. It looks as if the italic correction is missing in
the second case.
The latex document
\documentclass[12pt]{article}
\usepackage{unicode-math}
\begin{document}
$T(t)\quad \hat{T}(t)$
\end{document}
in texlive 2016 pretest shows the same problem, while in texlive
2015 everything was fine.
Is this an engine problem or a problem of the font loader?
--
Ulrike Fischer
http://www.troubleshooting-tex.de/