表格中跨行对齐

Question

\begin{table} 
\centering 
\renewcommand{\arraystretch}{1.3}
\begin{tabular}{c | l}
Group element & $U(\theta)=e^{\theta^a T_a}$ \\ 
\hline 
Algebra & $\begin{array} {r@{}l@{}} [T_a,T_b] & {}= f_{ab}{}^c T_c \\ f_{ab}{}^c & {}= \epsilon_{ab}{}^c \end{array}$ \\  \hline 
Connection & $A_\mu = A_\mu{}^a T_a$  \\  \hline 
Curvature & $\begin{array} {r@{}l@{}} R_{\mu\nu} & {}= R_{\mu\nu}{}^a T_a \\ R_{\mu\nu}{}^a & {}= 2 \partial_{\mu}A_{\nu]} + f{ab}{}^c A_\mu{}^b A_\nu{}^c \end{array}$ \\
\end{tabular}
\end{table}

有人能指出我该如何对齐右侧列中的等号吗？