The $$Z_c(3900)$$ Zc(3900) peak does not come from the “triangle singularity”

Abstract

Abstract We compare contributions from the triangle diagram and the $$D\bar{D}^*$$ DD¯∗ bubble chain with the processes of $$e^{+}e^{-}\rightarrow J/\psi \pi ^{+}\pi ^{-}$$ e+e-→J/ψπ+π- and $$e^{+}e^{-}\rightarrow (D\bar{D}^*)^\mp \pi ^{\pm }$$ e+e-→(DD¯∗)∓π± . By fitting the $$J/\psi \pi $$ J/ψπ maximum spectrum and the $$D\bar{D}^*$$ DD¯∗ spectrum, we find that the triangle diagram cannot explain the new experimental results from BESIII Collaboration at center of mass at 4.23 and 4.26 GeV, simultaneously. On the contrary, the molecular assignment of $$Z_c(3900)$$ Zc(3900) gives a much better description.