Fully heavy tetraquark states with a diquark-antidiquark configuration

The study of the fully heavy tetraquark state helps to better understand the characteristics of compact exotic hadrons formed by quarks and gluons. In this work, we systematically investigate the mass spectra and decay channels of fully heavy tetraquark states using a diquark-antidiquark model based on the one-gluon exchange process. The tetraquark states are treated as compact diquark-antidiquark configurations, denoted as $[QQ][\bar{Q}\bar{Q}]$, where $Q = c$ or $b$. By properly accounting for the Pauli principle, basis wave functions incorporating flavor, color, and spin are constructed. The required model parameters are derived from fitting conventional hadron experimental values and lattice QCD calculations. We calculate the mass spectra and decays of the fully heavy tetraquarks in the lower $S$ and $P$ waves. Our results do not support interpreting $X(6600)$, $X(6900)$, and $X(7200)$ as the $1S$-wave fully charmed tetraquark states. Nevertheless, our analysis suggests that $X(6200)$ can be a good candidate for the $1S$-wave fully charmed tetraquark state with quantum numbers $2^{++}$. Furthermore, we also identify several narrow fully heavy tetraquark states that may be observable in future experiments.