Revisit the tetraquark candidates in the $J/\psi J/\psi$ mass spectrum

TL;DR

This paper uses QCD sum rules to revisit fully-charm tetraquark states, introducing a relative P-wave in diquark operators, and suggests the broad structure above the $J/9 J/9$ threshold may consist of multiple tetraquark states.

Contribution

It introduces a new P-wave diquark operator to study fully-charm tetraquarks and analyzes their mass spectrum, providing insights into the structure of observed states.

Findings

Ground and excited tetraquark states have nearly degenerate masses.

The broad structure above the $J/9 J/9$ threshold may include multiple tetraquark states.

Abstract

In this article, we introduce a relative P-wave to construct the doubly-charm axialvector diquark operator, then take the doubly-charm axialvector (anti)diquark operator as the basic constituent to construct the scalar and tensor tetraquark currents to study the scalar, axialvector and tensor fully-charm tetraquark states with the QCD sum rules. We observe that the ground state $\tilde{A}\tilde{A}$ type tetraquark states and the first radial excited states of the $AA$ type tetraquark states have almost degenerated masses, where the $\tilde{A}$ and $A$ stand for the diquark operators with and without the relative P-wave respectively, the broad structure above the $J/\psi J/\psi$ threshold maybe consist of several diquark-antidiquark type fully-charm tetraquark states.