Reproducing $Z_c(3900)$ through the ISPE mechanism

Being stimulated by the recent BESIII observation of a charged charmonium-like structure $Z_c(3900)$, in this work we study the distributions of the $J/\psi\pi^\pm$ and $\pi^+\pi^-$ invariant mass spectra of the $Y(4260)\to \pi^+\pi^- J/\psi$ decays by the initial single pion emission (ISPE) mechanism, where the interference effect of ISPE mechanism with other two decay mechanisms is also considered. The obtained $d\Gamma(Y(4260)\to \pi^+\pi^- J/\psi)/dm_{J/\psi \pi^\pm}$ and $d\Gamma(Y(4260)\to \pi^+\pi^- J/\psi)/dm_{\pi^+ \pi^-}$ agree with the BESIII data, especially reproducing the $Z_c(3900)$ structure.