Systematics of fully heavy tetraquarks

TL;DR

This paper systematically analyzes the mass spectrum of fully heavy tetraquarks using an extended chromomagnetic model, revealing the dominance of color-sextet configurations and predicting potential narrow states.

Contribution

It introduces an extended chromomagnetic model to study heavy tetraquarks, highlighting the importance of color interactions and identifying possible narrow states.

Findings

Color-sextet configurations are energetically favored.

No stable states below heavy quarkonium pair thresholds.

Potential narrow state at 15719.1 MeV with specific quantum numbers.

Abstract

In this work, we systematically study the mass spectrum of the fully heavy tetraquark in an extended chromomagnetic model, which includes both color and chromomagnetic interactions. Numerical results indicate that the energy level is mainly determined by the color interaction, which favors the color-sextet $\ket{(QQ)^{6_{c}}(\bar{Q}\bar{Q})^{\bar{6}_{c}}}$ configuration over the color-triplet $\ket{(QQ)^{\bar{3}_{c}}(\bar{Q}\bar{Q})^{3_{c}}}$ one. The chromomagnetic interaction mixes the two color configurations and gives small splitting. The ground state is always dominated by the color-sextet configuration. We find no stable state below the lowest heavy quarkonium pair thresholds. Most states may be wide since they have at least one $S$-wave decay channel into two $S$-wave mesons. One possible narrow state is the $1^{+}$ $bb\bar{b}\bar{c}$ state with a mass $15719.1~\text{MeV}$. It is just above the $\eta_{b}\bar{B}_{c}$ threshold. But this channel is forbidden because of the conservation of the angular momentum and parity.