Analysis of the hidden-charm-hidden-strange tetraquark mass spectrum via the QCD sum rules

TL;DR

This paper uses QCD sum rules to analyze the mass spectrum of hidden-charm-hidden-strange tetraquarks, updating previous calculations and providing new identifications for several observed exotic states.

Contribution

It presents a comprehensive and updated QCD sum rule analysis of tetraquark states, including SU(3) breaking effects and new state identifications.

Findings

Revised mass spectrum predictions for tetraquark states.

New assignments for observed exotic states like X(3960) and X(4140).

Identification of LHCb states h_c(4000) and χ_c1(4010).

Abstract

In the present work, we construct the diquark-antidiquark type four-quark currents to investigate the mass spectrum of the ground state hidden-charm-hidden-strange tetraquark states with the quantum numbers $J^{PC}=0^{++}$, $1^{+-}$, $1^{++}$ and $2^{++}$ via the traditional QCD sum rules in a comprehensive way. We update old calculations, perform new calculations and analysis in a rigorous way, and take account of the net light-flavor $SU(3)$ breaking effects in a consistent way. And we make more reasonable identifications for the $X(3960)$, $X(4140)$, $X(4274)$, $X(4500)$, $X(4685)$ and $X(4700)$ and supersede some old identifications. Furthermore, we consider our previous theoretical predictions, and make reasonable/suitable identifications of the new LHCb states $h_c(4000)$ and $\chi_{c1}(4010)$.