Decay of $B_c^{*+}(3S) \to B^+D^0$
  The decay constant for the vector state of $3S$-level in the heavy $(\bar b c)$-quarkonium is evaluated in the framework of sum rules for the mesonic currents. A scaling relation for the constants of vector quarkonia with different quark contents is derived. The numerical estime gives $\Gamma(B_c^{*+}(3S)\to B^+D^0)=90 \pm 35$ MeV. 
V.V.Kiselev