Searching $B_c^{\ast }$ via conservation laws

To distinguish $B_c^{\ast +}(1^3{S}_1)$ and $B_c^{+}(1^1{S}_0)$ in the experiments, we propose two methods based on the conservation laws. I. From the angular momentum conservation, a nonzero helicity of $J\mathrm{/}\psi$ of $B_c^{(\ast)+ } \to J/\psi \pi^+$wouldbeanevidenceof$B_c^{\ast +}$\mathrm{.}II\mathrm{.}Since$B_c^+ \to B^+ \phi$iskinematicallyforbidden,$ B_c^{\ast +} \to B^+ \phi$ provides a clean channel to probe $B_c^{\ast +}$,. Particularly, our results show that $B_c^{\ast +}$ is promising to be observed at LHC via $B_c^{(\ast)+} \to J/\psi \pi^+$\mathrm{.}Ontheotherhand,wefindthat${\cal B} ( B_c^{\ast+} \to B^+ \phi) = ( 7.0 \pm 3.0 ) \times 10 ^{-9} $, which is also feasible to be measured at the forthcoming experiments at HL-LHC and FCC-hh.