Investigating the internal structure of $X(6900)$ in the $2J/\psi$ decay channel

TL;DR

This paper models the internal structure of the $X(6900)$ tetraquark state, calculating its decay width into $2J/$ using a covariant quark model, and finds the axial-vector--axial-vector coupling aligns with experimental data.

Contribution

It introduces a covariant quark model analysis of $X(6900)$ decay, comparing vector and axial-vector structures, and identifies the latter as consistent with observations.

Findings

Axial-vector--axial-vector coupling matches experimental decay widths.

Vector-vector coupling is less consistent with experimental data.

Supports the tetraquark interpretation of $X(6900)$.

Abstract

Assuming $X(6900)$ is a tetraquark state, the decay width of $X(6900)\to 2J/\psi$ is calculated in a covariant quark model, with the diquark-antidiquark $[cc][\bar{c}\bar{c}]$ picture. Two possible structures, vector-vector and axial-vector--axial-vector coupling, are investigated. The result indicates that the axial-vector--axial-vector coupling is consistent with the experiments.