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 $$ \sqrt{s} $$ < 0.883 GeV

Abstract 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 $$ \sqrt{s} $$ < 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 $$ \sqrt{s} $$ > 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.

Abstract licence: CC BY

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