Using $X(3823)\to J/\psi {\pi }^{+}{\pi }^{-}$ to identify coupled-channel effects

Abstract

Very recently, the Belle and BESIII experiments observed a new charmonium-like state $X(3823)$, which is a good candidate for the $D$-wave charmonium $\psi (1^3{D}_2)$. Because the $X(3823)$ is just near the $D{\bar{D}}^{\ast }$ threshold, the decay $X(3823)\to J/\psi {\pi }^{+}{\pi }^{-}$ can be a golden channel to test the significance of coupled-channel effects. In this work, this decay is considered including both the hidden-charm dipion and the usual quantum chromodynamics multipole expansion (QCDME) contributions. The partial decay width, the dipion invariant mass spectrum distribution $\mathrm{d}\Gamma [X(3823)\to J/\psi {\pi }^{+}{\pi }^{-}]/\mathrm{d}{m}_{{\pi }^{+}{\pi }^{-}}$, and the corresponding $\mathrm{d}\Gamma [X(3823)\to J/\psi {\pi }^{+}{\pi }^{-}]/\mathrm{d}\cos \theta$ distribution are computed. Many parameters are determined from existing experimental data, so the results depend mainly only on one unknown phase between the QCDME and hidden-charm dipion amplitudes.

Comments: 8 pages, 1 table, 5 figures. Accepted by Frontiers of Physics