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

Abstract

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 $J/\psi$ of $B_c^{(\ast )+}\to J/\psi {\pi }^{+}$ would be an evidence of $B_c^{\ast +}$. II. Since $B_c^{+}\to B^{+}\varphi$ is kinematically forbidden, $B_c^{\ast +}\to B^{+}\varphi$ 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 $B_c^{(\ast )+}\to J/\psi {\pi }^{+}$. On the other hand, we find that $\mathcal{B}(B_c^{\ast +}\to B^{+}\varphi )=(7.0\pm 3.0)\times 10^{-9}$, which is also feasible to be measured at the forthcoming experiments at HL-LHC and FCC-hh.

Comments: 15 pages, 4 figures. Accepted by PRD