subscript smaller than underbrace breaks alignment

Question

I have this

I have two problems: First, as you might see, when the subscript is smaller than the text in the underbrace the alignment is broken (but if the subscript is longer the alignment works perfectly). The second problem is I'm trying that the text 'parameter set' is blue and NOT bold. Is this possible? (you can avoid using the command as I just use it because I use bold and blue a lot)

For an underbrace in a subscript, I'm using this solution. And when I try the solution for subscript smaller than underbrace I got this: (I replace \underbrace by \textunderbrace in the code below for this output, as stated in the solution linked)

The code:

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{xcolor}
\newcommand\boldblue[1]{\textcolor{blue}{\textbf{#1}}}
\begin{document}
\boldblue{$(E,{P_\theta}{\underbrace{\scriptstyle{\theta \in \Theta}}\text{parameter set}})$}
\end{document}

PS: I would like to keep it simple, so I would prefer to avoid using more packages than AMS and xcolor.

score 2 · Accepted Answer · answered Jun 21 '21 at 05:25

Something like this?

\documentclass{article}
\usepackage{mathtools,xcolor}
\newcommand\boldblue[1]{{\color{blue}\bfseries #1}}
\begin{document}
\boldblue{($E$,${P_\theta}^{}_{%
    \underbrace{\scriptstyle\theta\in\Theta}%
    _{\mathclap{\textnormal{parameter set}}}}$)}
\end{document}

subscript smaller than underbrace breaks alignment

1 Answers1