[Tex/LaTex] align text and equations in columns in beamer

alignbeamerequationsvertical alignment

I have a beamer frame consisting of two columns (top aligned) using the [T] option. The second column contains a align equation block. Even though I am using the [T] option the column containing the equation will not align with the text in the left column. When a put a line of text just before the equation the alignment works fine. So what am I missing ?

Here is a MWE

\documentclass{beamer}
\DeclareMathOperator{\IM}{Im}
\begin{document}
\newcommand{\highlight}[1]{\colorbox{yellow}{$\displaystyle #1$}}
\begin{frame}
    \begin{columns}[T]
        \column{0.4\textwidth}
        Transverse MO Kerr effect
        {\tiny [Zvezdin, Modern Magnetooptics, IOP 1999]}
        \column{0.6\textwidth}
        %\centering test
        \begin{align*}
        r_p(M) &= r^0_p\left(1+i\rho_p(M)\right)\\
        \rho_p(M) &=\frac{-ir_p^0\epsilon_g(M)/\epsilon_z\sin\varphi}{2(\eta^2-\sin^2\varphi)^{1/2}}\\
            [r_s(M) &= r^0_s\quad\eta =n/n_\mathrm{inc}]\\
            \delta_p &= \frac{I(M)-I_0}{I_0} = \highlight{2\IM(\rho_p)} %\quad \textcolor{red}{\textbf{\only on lossy MO materials}}
        \end{align*}\par
        \centering$\color{red}\Rightarrow$ \textcolor{red}{\textbf{only on lossy MO materials}}
    \end{columns}

\end{frame}

\begin{frame}
    \begin{columns}[T]
        \column{0.4\textwidth}
        Transverse MO Kerr effect
        {\tiny [Zvezdin, Modern Magnetooptics, IOP 1999]}
        \column{0.6\textwidth}
        \centering test
        \begin{align*}
        r_p(M) &= r^0_p\left(1+i\rho_p(M)\right)\\
        \rho_p(M) &=\frac{-ir_p^0\epsilon_g(M)/\epsilon_z\sin\varphi}{2(\eta^2-\sin^2\varphi)^{1/2}}\\
            [r_s(M) &= r^0_s\quad\eta =n/n_\mathrm{inc}]\\
            \delta_p &= \frac{I(M)-I_0}{I_0} = \highlight{2\IM(\rho_p)} %\quad \textcolor{red}{\textbf{\only on lossy MO materials}}
        \end{align*}\par
        \centering$\color{red}\Rightarrow$ \textcolor{red}{\textbf{only on lossy MO materials}}
    \end{columns}

\end{frame}

\end{document}

Best Answer

align will have \abovedisplayskip above the its top. You have to get rid of it. Plus since making it zero will bring the equation in the next line (display equation!) making 

\setlength{\abovedisplayskip}{-\baselineskip}

will do the job. Further, you need to add a `\par in

{\tiny [Zvezdin, Modern Magnetooptics, IOP 1999]\par}

Code:

\documentclass{beamer}
\DeclareMathOperator{\IM}{Im}
\begin{document}
\newcommand{\highlight}[1]{\colorbox{yellow}{$\displaystyle #1$}}
\begin{frame}
    \begin{columns}
        \column[t]{0.4\textwidth}
        Transverse MO Kerr effect
        {\tiny [Zvezdin, Modern Magnetooptics, IOP 1999]\par}   %% you need a \par here
        \column[t]{0.6\textwidth}
        \setlength{\abovedisplayskip}{-\baselineskip}
        %\centering test
        \begin{align*}
        r_p(M) &= r^0_p\left(1+i\rho_p(M)\right)\\
        \rho_p(M) &=\frac{-ir_p^0\epsilon_g(M)/\epsilon_z\sin\varphi}{2(\eta^2-\sin^2\varphi)^{1/2}}\\
            [r_s(M) &= r^0_s\quad\eta =n/n_\mathrm{inc}]\\
            \delta_p &= \frac{I(M)-I_0}{I_0} = \highlight{2\IM(\rho_p)} %\quad \textcolor{red}{\textbf{\only on lossy MO materials}}
        \end{align*}\par
        \centering$\color{red}\Rightarrow$ \textcolor{red}{\textbf{only on lossy MO materials}}
    \end{columns}

\end{frame}
\end{document}

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