\begin{table}%t1 
%\centering
\par
\caption{Summary of the parameter space under investigation.}\label{Tab:Params} 
\small{\begin{tabular}{c@{\extracolsep{1.25cm}}c}  
\hline\hline 
group~1 & group~2 \\ 
\hline 
$B_0=\{1.0,2.0,3.0,5.0,9.0\}$ & $B_0=2.9$ \\ 
$\alpha=0.4$ & $\alpha=\{0.1,0.2,0.3\}$\\ 
\hline 
\end{tabular}}
\end{table}