First order power corrections to current matrix elements between heavy meson or $\Lambda_\Q$ baryon states are shown to vanish at the zero recoil point to all orders in QCD. Five relations among the six form factors that parametrize the semileptonic decay $\Lambda_b \to \Lambda_c e \overline{ \nu}$ are also demonstrated to exist to all orders in the strong coupling at order $1/\mQ$ . The $O(\bas(m_c)/m_c)$ form factor relations are displayed.
Categories: hep-ph