Fit to the LHCb double $J/\psi$ spectrum

This is a coupled-channel analysis of the LHCb data reporting the $X(6900)$ in arXiv:2006.18957. Our results are presented in arXiv:2009.07795.

We consider coupled channels of two kinds:

• two channels: $J/\psi J/\psi$ and $J/\psi \psi(2S)$
• three channels: $J/\psi J/\psi$, $J/\psi \psi(2S)$ and $J/\psi \psi(3770)$

The analysis can be played interactively by clicking