Measurement of $e^{+}e^{-}\rightarrowωπ^{+}π^{-}$ cross section at $\sqrt s = $ 2.000 to 3.080 GeV

Abstract

A partial wave analysis on the process $e^{+}e^{-}\rightarrowωπ^{+}π^{-}$ is performed using 647 pb$^{-1}$ of data sample collected by using the BESIII detector operating at the BEPCII storage ring at center-of-mass (c.m.) energies from 2.000 GeV to 3.080 GeV. The Born cross section of the $e^{+}e^{-}\rightarrowωπ^{+}π^{-}$ process is measured, with precision improved by a factor of 3 compared to that of previous studies. A structure near 2.25 GeV is observed in the energy-dependent cross sections of $e^{+}e^{-}\toωπ^{+}π^{-}$ and $ωπ^{0}π^{0}$ with a statistical significance of 7.6$σ$, and its determined mass and width are 2232 $\pm$ 19 $\pm$ 27 MeV$/c^{2}$ and 93 $\pm$ 53 $\pm$ 20 MeV, respectively, where the first and second uncertainties are statistical and systematic, respectively. By analyzing the cross sections of subprocesses $e^{+}e^{-}\rightarrow ωf_{0}(500)$, $ωf_{0}(980)$, $ωf_{0}(1370)$, $ωf_{2}(1270)$, and $b_{1}(1235)π$, a structure, with mass M = 2200 $\pm$ 11 $\pm$ 17 MeV/$c^2$ and width $Γ$ = 74 $\pm$ 20 $\pm$ 24 MeV, is observed with a combined statistical significance of 7.9$σ$. The measured resonance parameters will help to reveal the nature of vector states around 2.25 GeV.