\documentclass[12pt]{article} \usepackage{amssymb,amsmath,amscd,concmath,amsfonts} \usepackage{color} \pagestyle{empty} \begin{document} \begin{equation*} \label{eq:osc:procmod} P(s)=\frac{\omega_0^2}{s^2+2\zeta \omega_0 s+\omega_0^2}, \end{equation*} \end{document}