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 − ) ℬ ( ρ (1450) → ηπ + π − ) and the Γ( ρ (1700) → e + e − ) 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 − π 0 ντ decay. The e + e − → ηπ + π − cross section obtained with the CMD-3 detector is in good agreement with the previous measurements.