One of the conferences requires paper submission in Helvetica Font. But the provided template uses standard math package, making the the document inconsistent.

This gist shared a way to set Helvetica Font without using XeLaTeX:

\renewcommand{\familydefault}{\sfdefault}
\usepackage[scaled=1]{helvet}
\usepackage[helvet]{sfmath}
\everymath={\sf}

This also applies to fonts other than Arial Narrow.

1. Use XeLaTeX instead of pdftex.
2. Suppose the desired font for mathematical symbols is Computer Modern Bright:

\usepackage{cmbright}
\usepackage[T1]{fontenc}
\usepackage[no-math]{fontspec} \setsansfont[Ligatures=TeX]{Arial Narrow}

3. Use \sffamily after \begin{document}.

Note: the other way to set font …