Measurement of the e ⁺ e ⁻ → π ⁺ π ⁻ process cross section with the SND detector at the VEPP-2000 collider in the energy region 0.525 < √s < 0.883 GeV

The cross section of the process e⁺e⁻ → π⁺π⁻ has been measured in the Spherical Neutral Detector (SND) experiment at the VEPP-2000 e⁺e⁻ collider VEPP-2000 in the energy region 525 <s< 883 MeV. The measurement is based on data with an integrated luminosity of about 4.6 pb⁻¹. The systematic uncertainty of the cross section determination is 0.8% at s> 0.600 GeV. The ρ meson parameters are obtained as m_ρ = 775.3 ± 0.5 ± 0.6 MeV, Γ_ρ = 145.6 ± 0.6 ± 0.8 MeV, B_ρ→e+e− × B_{ρ→π+π−} = (4.89 ± 0.02 ± 0.04) × 10⁻⁵, and the parameters of the e⁺e⁻ → ω → π⁺π⁻ process, suppressed by G-parity, as B_ω→e+e− × B_{ω→π+π−} = (1.32 ± 0.06 ± 0.02) × 10⁻⁶ and and ϕ_ρω = 110.7 ± 1.5 ± 1.0 degrees.