Vertical align in a table

Question

I have the following code:

\begin{table}[H]  
\begin{center}  
\caption{Quarks and leptons of the Standard Model.}  
\label{TablaQuarks}  
\begin{tabu}{|m{2cm}|m{2cm}|m{4cm}|[2pt]} \hline  
\multicolumn{3}{|c|[2pt]}{Quarks} \\ \hline  
Flavour & Charge & Mass \\ \hline  
u & 2/3 $e$ & 2.3$_{-0.5}^{+0.7}$ MeV/c$^2$ \\[1.0ex]  
d & -1/3 $e$ & 4.8$_{-0.3}^{+0.7}$ MeV/c$^2$ \\[1.0ex]\hline  
c & 2/3 $e$ & 1.275 $\pm$ 0.025 GeV/c$^2$ \\  
s &  -1/3 $e$ & 95 $\pm$ 5 MeV/c$^2$ \\ \hline  
t & 2/3 $e$ & 173.5 $\pm$ 0.6 GeV/c$^2$ \\  
b &  - 1/3 $e$ & 4.18 $\pm$ 0.03 GeV/c$^2$ \\ \hline  
\end{tabu}
\end{center}  
\end{table}

The problem is that I cannot center (vertically) the text in the last column, it always remains at the top. Moreover the first two that are vertically aligned cannot be centered horizontally.

In order to use the previous code you need the tabu and array packages.

Answer 1

It's best not to use \\[length] if the last column is a multi-line entry. This version opens out the table so that isn't needed, and applies \centering to the cells. I left in the [H] from your MWE but that shouldn't ever really be needed.

\documentclass{article}
\usepackage{tabu,float}
\begin{document}
\begin{table}[H]  
\begin{center}  
\caption{Quarks and leptons of the Standard Model.} 
\smallskip
\label{TablaQuarks}  
\setlength\extrarowheight{5pt}
\begin{tabu}{
|>{\centering}m{2cm}|
>{\centering}m{2cm}|
>{\centering\arraybackslash}m{4cm}|[2pt]} \hline  
\multicolumn{3}{|c|[2pt]}{Quarks} \\ \hline  
Flavour & Charge & Mass \\ \hline  
u & 2/3 $e$ & 2.3$_{-0.5}^{+0.7}$ MeV/c$^2$ \\
d & -1/3 $e$ & 4.8$_{-0.3}^{+0.7}$ MeV/c$^2$ \\\hline  
c & 2/3 $e$ & 1.275 $\pm$ 0.025 GeV/c$^2$ \\  
s &  -1/3 $e$ & 95 $\pm$ 5 MeV/c$^2$ \\ \hline  
t & 2/3 $e$ & 173.5 $\pm$ 0.6 GeV/c$^2$ \\  
b &  - 1/3 $e$ & 4.18 $\pm$ 0.03 GeV/c$^2$ \\ \hline  
\end{tabu}
\end{center}  
\end{table}

\end{document}

Answer 2

The problem with the vertical alignment happens because the formula takes too much vertical space, so you need to open the lines a bit.

While thinking about your issues I got motivated to write my own version of your table in plain TeX, including (in my opinion) some typographical improvements:

• the spacing between the numbers and the units

• the kerning between the V and / in GeV/c^2

• the centering of the charges irrespective of the minus sign and moving the unit (e) to the definition of the column

• using right alignment for the masses, except for the column name which is centered

The issue with the vertical spacing I solved by defining a macro \openline#1 which inserts some points of vertical space.

You can copy&paste the table in your latex document too, it works with no modifications.

\def\hline{\noalign{\hrule}}
\def\openlineAux#1{height#1pt&\omit&\omit&\omit&height#1pt\cr}
\def\openline#1{\openlineAux#1\hline\openlineAux#1}

\vbox{\offinterlineskip
\halign{&\vrule#&\hfil#\hfil &\quad\hfil#\hfil &\quad\hfil#&\vrule#\cr
\hline\openlineAux3
&\multispan3 \hfil Quarks\hfil&\cr
\openline3
&\enskip\strut Flavour & Charge ($e$) & Mass \hfil&\cr
\openline3
&u & $\phantom{-}2/3$  & $2.3_{-0.5}^{+0.7}\; \rm MeV\!/c^2$ &\cr
\openline3
&d & $-1/3$  & $4.8_{-0.3}^{+0.7}\; \rm MeV\!/c^2$ &\cr
\openline3
&c & $\phantom{-}2/3$  & $1.275 \pm 0.025\; \rm GeV\!/c^2$ &\cr
\openline2
&s &  $-1/3$  & $95 \pm 5\; \rm MeV\!/c^2$  &\cr
\openline2
&t & $\phantom{-}2/3$  & $173.5 \pm 0.6\; \rm GeV\!/c^2$ &\cr
\openline2
&b &  $- 1/3$ & $4.18 \pm 0.03\; \rm GeV\!/c^2$ &\cr
\openlineAux2\hline
}}