Cross section of the reaction e+e−→π+π−π+π− below 1 GeV at CMD-2

Using 3.07 pb−1 of data collected in the energy range 0.60–0.97 GeV by CMD-2, about 150 events of the process e+e−→π+π−π+π− have been selected. The energy dependence of the cross section agrees with the assumption of the a1(1260)π intermediate state which is dominant above 1 GeV. For the first time π+π−π+π− events are observed at the ρ meson energy. Under the assumption that all these events come from the ρ meson decay, the value of the cross section at the ρ meson peak corresponds to the following decay width:Γ(ρ0→π+π−π+π−)=(2.8±1.4±0.5) keVor to the branching ratioB(ρ0→π+π−π+π−)=(1.8±0.9±0.3)·10−5.