The $X(6900)$ peak could be a molecular state

TL;DR

This paper analyzes LHCb data on the $X(6900)$ peak using a Flatté-like parameterization, concluding it may not be a $J/\psi \psi(3686)$ molecule but could be a molecule of higher states.

Contribution

It applies a momentum-dependent Flatté-like parameterization and spectral density sum rule to analyze the nature of $X(6900)$, providing new insights into its possible molecular composition.

Findings

$X(6900)$ likely not a $J/\psi \psi(3686)$ molecule

Possible $X(6900)$ molecules include higher states like $J/\psi \psi(3770)$

Consistent conclusions from pole counting and spectral density sum rules

Abstract

The analyses of the LHCb data on $X(6900)$ found in di-$J/\psi$ and $J/\psi \psi(3686)$ systems are performed using a momentum-dependent {Flatt\'{e}}-like parameterization. The use of the pole counting rule and spectral density function sum rule give consistent conclusions that $X(6900)$ may not be a molecule of $J/\psi \psi(3686)$. Nevertheless it is still possible that $X(6900)$ be a molecule of higher states, such as $J/\psi\psi(3770)$, $\chi_{c0}\chi_{c2}$, etc.