Contributions of $\psi_{2}(3823)$ and $\psi(4040)$ charmonium in $B^+\rightarrow J/\psi\eta K^+$ decay

Abstract

Recently, a study on the $J/\psi\eta$ mass spectrum from $B^+\rightarrow J/\psi\eta K^+$ decays was reported by the LHCb detector. The results of this study are reported as a ratio of branching fractions as $F_{X}\equiv\frac{\mathcal{B}r(B^+\rightarrow XK^+)\times\mathcal{B}r(X\rightarrow J/\psi\eta)}{\mathcal{B}r(B^+\rightarrow \psi(2S) K^+)\times\mathcal{B}r(\psi(2S)\rightarrow J/\psi\eta)}$ for $X=\psi_2(3823),\psi(4040)$, which are $(5.95^{+3.38}_{-2.55})\times10^{-2}$ and $(40.60\pm11.20)\times10^{-2}$, respectively. Also, the products related to $B_{X}\equiv\mathcal{B}r(B^+\rightarrow XK^+)\times\mathcal{B}r(X\rightarrow J/\psi\eta)$ branching fractions are $B_{\psi_2(3823)}=(1.25^{+0.71}_{-0.53}\pm0.04)\times10^{-6}$ and $B_{\psi(4040)}=(8.53\pm2.35\pm0.30)\times10^{-6}$. For the first time, we calculated this branching fraction using factorization. According to our calculations, $F_X$ to be $F_{\psi_{2}(3823)}=(6.55\pm1.88)\times10^{-2}$ and $F_{\psi(4040)}=(14.33\pm4.15)\times10^{-2}$ at $\mu=m_b/2$. We have estimated $B_{\psi_{2}(3823)}=(0.26\pm0.05)\times10^{-6}$ at $\mu=m_b/2$ and $B_{\psi(4040)}=(2.88\pm0.64)\times10^{-6}$ at $\mu=2m_b$.