Formula_17562

\[\begin{gathered}\left\langle\mathrm{B} \pi^{\alpha}|H(0)| \mathrm{A}\right\rangle_{q \rightarrow 0} \rightarrow \\\rightarrow i f_{\pi}^{-1}\left\langle\mathrm{~B}\left|\left[H(0), \int A_{0}^{\alpha}(x) d^{3} x\right]_{x_{0}=0}\right| \mathrm{A}\right\rangle,\end{gathered}\]