Comparison of1mQ2corrections in mesons and baryons

We extend our relativistic quark model to the study of the decay ${\Lambda }_b\to {\Lambda }_c\ell \overline{\nu }$ and verify that the model satisfies the heavy-quark symmetry constraints at order $\frac{1}{m_Q^2}$. We isolate a strong dependence on a parameter which measures the relative distortion in the light-quark wave functions of the ${\Lambda }_b$ and ${\Lambda }_c$. This parameter and the $\frac{1}{m_Q^2}$ corrections are naturally small. The dependence on a corresponding parameter in the meson case leads to large $\frac{1}{m_Q^2}$ corrections which, if ignored, would lead to an apparent discrepancy between $\left|V_{\mathrm{cb}}\right|$ extracted from baryon and meson semileptonic decays.