Observation of e+e- Annihilation into the C=+1 Hadronic Final States ρ0ρ0 and ϕρ0

We report the first observation of e+e- annihilation into states of positive C parity, namely, ρ0ρ0 and ϕρ0. The two states are observed in the π+π-π+π- and K+K-π+π- final states, respectively, in a data sample of 225  fb-1 collected by the BABAR experiment at the Positron-Electron Project II e+e- storage rings at energies near √s=10.58  GeV. The distributions of cos⁡θ*, where θ* is the center-of-mass polar angle of the ϕ meson or the forward ρ0 meson, suggest production by two-virtual-photon annihilation. We measure cross sections within the range |cos⁡θ*|<0.8 of σ(e+e-→ρ0ρ0)=20.7±0.7(stat)±2.7(syst)  fb and σ(e+e-→ϕρ0)=5.7±0.5(stat)±0.8(syst)  fb.