Strong decays of fully-charm tetraquarks into di-charmonia

TL;DR

This paper analyzes the strong decay patterns of fully-charm tetraquarks observed at LHCb, proposing their quantum numbers, interpreting experimental structures, and suggesting new channels for confirmation and partner state searches.

Contribution

It provides a theoretical interpretation of observed tetraquark structures and predicts decay channels for experimental verification, extending previous QCD sum rule results.

Findings

Broad structure around 6.2-6.8 GeV likely an S-wave $cc\bar c \bar c$ tetraquark

Narrow structure around 6.9 GeV possibly a P-wave tetraquark

Proposes new decay channels for experimental confirmation

Abstract

We study strong decays of the possible fully-charm tetraquarks recently observed by LHCb, and calculate their relative branching ratios through the Fierz rearrangement. Together with our previous QCD sum rule study [Phys. Lett. B 773, 247 (2017)], our results suggest that the broad structure around $6.2$-$6.8$ GeV can be interpreted as an $S$-wave $cc\bar c \bar c$ tetraquark state with $J^{PC} = 0^{++}$ or $2^{++}$, and the narrow structure around 6.9 GeV can be interpreted as a $P$-wave one with $J^{PC} = 0^{-+}$ or $1^{-+}$. These structures were observed in the di-$J/\psi$ invariant mass spectrum, and we propose to confirm them in the di-$\eta_c$, $J/\psi h_c$, $\eta_c \chi_{c0}$, and $\eta_c \chi_{c1}$ channels. We also propose to search for their partner states having the negative charge-conjugation parity in the $J/\psi \eta_c$, $J/\psi \chi_{c0}$, $J/\psi \chi_{c1}$, and $\eta_c h_c$ channels.