Decays of $1^{-+}$ Charmoniumlike Hybrid

TL;DR

This paper provides the first lattice QCD predictions for the decay widths of the $1^{-+}$ charmoniumlike hybrid $ ext{eta}_{c1}$, highlighting dominant open charm decay modes and suggesting experimental search strategies.

Contribution

The study offers the first lattice QCD calculation of decay widths for the $1^{-+}$ charmoniumlike hybrid, including detailed decay mode analysis and experimental search suggestions.

Findings

Mass of $ ext{eta}_{c1}$ is 4.329 GeV.

Dominant decay modes are $D_1ar{D}$, $D^*ar{D}$, and $D^*ar{D}^*$.

Partial widths for these modes are approximately 258 MeV, 88 MeV, and 150 MeV.

Abstract

By extracting the transition amplitudes, we give the first lattice QCD prediction of the two-body decay partial widths of the $1^{-+}$ charmoniumlike hybrid $\eta_{c1}$. Given the calculated mass value $m_{\eta_{c1}}=4.329(36)$ GeV, the $\eta_{c1}$ decay is dominated by the open charm modes $D_1\bar{D}$, $D^*\bar{D}$ and $D^*\bar{D}^*$ with partial widths of $258(133)$ MeV, $88(18)$ MeV and $150(118)$ MeV, respectively. The coupling of $\eta_{c1}$ to $\chi_{c1}$ plus a flavor singlet pseudoscalar is not small, but $\chi_{c1}\eta$ decay is suppressed by the small $\eta-\eta'$ mixing angle. The partial width of $\eta_{c1}\to \eta_c\eta'$ is estimated to be around 1 MeV. We suggest experiments to search for $\eta_{c1}$ in the $P$-wave $D^*\bar{D}$ and $D^*\bar{D}^*$ systems. Especially, the polarization of $D^*\bar{D}^*$ can be used to distinguish the $1^{-+}$ product (total spin $S=1$) from $1^{--}$ products ($S=0$).