$S$-wave fully charmed tetraquark resonant states

TL;DR

This study predicts the existence of multiple fully-charmed tetraquark resonances using a nonrelativistic quark model, providing theoretical mass and width estimates that align with some experimental observations.

Contribution

It presents the first calculation of $S$-wave fully-charmed tetraquark resonances using the Gaussian expansion and complex scaling methods within a nonrelativistic quark model.

Findings

Identified two resonances in each of the $J^{PC}=$ $0^{++}$, $1^{+-}$, and $2^{++}$ sectors.

Resonance energies are around 100 MeV above the $X(6900)$ state, with decay widths consistent with experimental data.

Predicted higher resonances at about 7.2 GeV potentially corresponding to the $X(7200)$ state.

Abstract

We calculate the mass spectrum of the $S$-wave fully-charmed tetraquark resonant states $cc\bar c\bar c $ in the nonrelativistic quark model, which successfully describes the charmonium spectrum. The four-body system is solved with the Gaussian expansion method. The complex scaling technique is used to identify the genuine resonances. With the nonrelativistic quark model, our results show the existence of two $cc\bar c\bar c$ resonances in each of the $J^{PC}=$ $0^{++}$, $1^{+-}$ and $2^{++}$ sectors, respectively. In the $S$-wave sector, no resonance is found at the energy region of the $X(6200)$ and $X(6600)$ states. The lower $0^{++}$ and $2^{++}$ resonances are located around $100$ MeV higher than the $X(6900)$ state observed in experiments but have the decay widths consistent with the experiment. The higher $0^{++}$ and $2^{++}$ resonances are found at around $7.2$ GeV with the widths of $60.6$ MeV and $91.2$ MeV, respectively, and they may be good candidates for the $X(7200)$ state.