Latex for M, m use in the context for major and minor arc

Question

How can we write these "M" here in Latex? especially Overleaf?

Answer 1

As mentioned @daleif in his comment:

\documentclass{article}
%\usepackage{libertine}
\usepackage[libertine]{newtxmath} % or other fonts which contain fraktur font 
                                  % see https://tug.org/FontCatalogue/fraktur/
\begin{document}
$\mathfrak{m}$  $\mathfrak{M}$
\end{document}