Discussions on the line-shape of the X(4660) resonance

A careful reanalysis is made on e+e-→X(4660)→(ΛcΛ¯c)/(ψ′ππ) processes, aiming at resolving the apparent conflicts between Belle and BESIII data above the ΛcΛ¯c threshold. We use a model containing a Breit-Wigner resonance and ΛcΛ¯c four-point contact interactions, with which the enhancement right above ΛcΛ¯c threshold is well explained by a virtual pole generated by ΛcΛ¯c attractive final state interaction, located at MV=4.566±0.007  GeV. Meanwhile, X(4660) remains to be a typical Breit-Wigner resonance, and is hence of confinement nature. Our analysis strongly suggests the existence of the virtual pole with statistical significance of 4.2 standard deviation (σ). Nevertheless, the conclusion crucially depends on the line-shape of cross sections which are of limited statistics, hence we urge new experimental analyses from Belle II, BESIII, and LHCb to settle the issue.