problem with showing \ae inside a formula in xelatex

Question

when i write an equation that contains $\ae$ and run it in xepersian, it won't show it and instead it shows a blank space. I can only write it in text by using \lr{\ae} or begin{latin}\ae\end{latin} but these two can not be used inside a formula. I tried this:

\begin{latin}
$\displaystyle \prod_{i=1}^n ($\lr{\ae}$)\pi$
\end{latin}

but it's not a good way, because when I run this code:

\begin{latin}
$\displaystyle \prod_{i=1}^n \left($\lr{\ae}$\right)\pi$
\end{latin}

it says \right is not defined!

this is my code:

\documentclass{article}
\usepackage{amsmath,amsxtra,amssymb,latexsym, amscd,amsthm}
\usepackage[extrafootnotefeatures]{xepersian}
\settextfont[Scale=1.3]{B Nazanin}
\begin{document}
$\to \ae \gets$  %this line gets error
\begin{latin}
\ae
\end{latin}
\lr{\ae}
\begin{latin}
$\displaystyle \prod_{i=1}^n ($\lr{\ae}$)\pi$
\end{latin}
\end{document}

and output is :