[Tex/LaTex] Vertical positioning of superscripts with different heights

subscriptssuperscripts

I'm trying to format some Clebsch-Gordan coefficients to look like this

good Clebsch

i.e. a normal C followed by a 2×3 array (using super/subscripts; not an actual LaTeX array) of indices. But instead of j_1, j_2, my indices have Greek subscripts such as l_\alpha, which is fine until I have l_\beta and it throws the alignment out as such:

bad Clebsch

\documentclass{book}
\begin{document}
\[ C{}^{\,\,l_\beta}_{m_\beta}{}^2_0{}^{\,\,l_\alpha}_{m_\alpha} \]
\end{document}

Interestingly, this only happens if the superscript has a _\beta; if it's only in the subscript there's no problem. It seems the low-hanging "tail" of the beta is pushing the whole superscript up and taking the subscript with it.

\usepackage{subdepth} doesn't help. I thought \vphantom{_\beta} could push everything up but that doesn't work well either. Is there any way to adjust the height of superscripts based on its top rather than its bottom? Or manually fine-tune its vertical position?

Best Answer

You can use a \mathstrut:

\documentclass{book}
\begin{document}
\[ C{\mathstrut}^{\,\,l_\beta}_{m_\beta}{\mathstrut}^2_0{\mathstrut}^{\,\,l_\alpha}_{m_\alpha} \]
\end{document}

enter image description here

Here is a proposition which may be fine tuned.

\documentclass{book}
\usepackage{amsmath}
\begin{document}
\[C\!%
\begin{smallmatrix}
l_{\beta} & \!\!2 & \!\!l_{\alpha} \\
m_{\beta} & \!\!0 & \!\!m_{\alpha}
\end{smallmatrix}
\]
\end{document}

enter image description here

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