$ϕ(2170)$ decaying to $ϕππ$ and $ϕK\bar{K}$

Abstract

Within the framework of dispersion theory, we study the the processes $e^+e^-\to ϕ(2170) \to ϕππ(K\bar{K})$. The strong pion-pion final-state interactions, especially the $K\bar{K}$ coupled channel in the $S$-wave, are taken into account in a model-independent way using the Omnès function solution. Through fitting the experimental data of the $ππ$ and $ϕπ$ invariant mass distributions of the $e^+e^- \to ϕ(2170) \to ϕπ^+π^-$ process, the low-energy constants in the chiral Lagrangian are determined. The theoretical prediction for the cross sections ratio ${σ(e^+e^- \to ϕ(2170)\to ϕK^+ K^-)}/{σ(e^+e^- \to ϕ(2170)\to ϕπ^+π^-)}$ is given, which could be useful for selecting the physical solution when the fit to the $e^+e^- \to ϕK^+ K^-$ cross section distribution is available in the future. Our results suggest that above the kinematical threshold of $ϕK\bar{K}$, the mechanism $e^+e^- \to ϕK^+ K^-$ with the kaons rescattering to a pion pair plays an important role in the $e^+e^- \to ϕπ^+π^-$ transition.