Measurement of the e+e−→ ηπ+π− cross section with the CMD-3 detector at the VEPP-2000 collider

The cross section of the process e+e−→ ηπ+π− is measured using the data collected with the CMD-3 detector at the VEPP-2000 collider in the center-of-mass energy range from 1.1 to 2.0 GeV. The decay mode η → γγ is used for η meson reconstruction in the data sample corresponding to an integrated luminosity of 78.3 pb−1. The energy dependence of the e+e−→ ηπ+π− cross section is fitted within the framework of vector meson dominance in order to extract the Γ(ρ(1450) → e+e−)$$ \mathcal{B} $$(ρ(1450) → ηπ+π−) and the Γ(ρ(1700) → e+e−)$$ \mathcal{B} $$(ρ(1700) → ηπ+π−) products. Based on conservation of vector current, the analyzed data are used to test the relationship between the e+e−→ ηπ+π− cross section and the spectral function in τ−→ ηπ−π0ντ decay. The e+e−→ ηπ+π− cross section obtained with the CMD-3 detector is in good agreement with the previous measurements.