  Despite the great success on the mass spectra, the reputation of the bag
model has been closely followed by the embarrassment from the center of mass
motion. It leads to severe theoretical inconsistencies. For instance, the
masses and the decay constants would no longer be independent of the momentum.
In this work, we provide a systematical approach to resolve this problem. The
meson decay constants as well as the baryon transition form factors can be
computed consistently in our framework. Notably, the form factors in the
neutron $\beta$ decays do not depend on any free parameters, and are determined
to be $F^V_1 =1 $ and $F^A_1 = 1.31$ or $F_1^A/F_1^V= 1.31$, which is close the
experimental value of $F^A_1/F^V_1 = 1.27$. In addition, we find that ${\cal B}
(\Lambda_b \to \Lambda \gamma) = (6.8 \pm 3.3 ) \times 10^{-6} $, which agrees
to the experimental value of $(7.1\pm 1.7)\times 10^{-6}$.
