 | Fits to the di-$J/\psi$ and $J/\psi+\psi$(2S) mass spectra in the SRs for model $A$ (top panel) and $B$ (bottom panel). For each model, the di-$J/\psi$ spectrum (left) and the $J/\psi+\psi$(2S) spectra in the $4\mu$ (middle) and $4\mu+2\pi$ (right) channels are shown. The purple dash-dotted lines represent the components of individual resonances, and the green short dashed ones represent the interferences. Note that no interference is present in the $J/\psi+\psi$(2S) channels with model $B$ since $X$(6900) is standalone. |