Mixing Angle of $\varXi_Q-\varXi_Q'$ in Heavy Quark Effective Therory

The Heavy Quark Effective Theory provides a systematic method to estimate a mixing angle of hadron states in a heavy quark, such as the charm quark (c) and the bottom quark (b). By using this method, the mixing angle of the baryons $\varXi_Q-\varXi_Q'$ can be estimated. It is found that the mixing angle between $\varXi_Q$ and $\varXi_Q'$ is given by $θ_b = 4.51^{\circ} \pm 0.79 ^{\circ}$ for $Q = b$ case and $θ_c = 8.12^{\circ} \pm 0.80 ^{\circ}$ for $Q = c$ case.