ISSN - 03702693, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 2000, vol. 475, p. 190-197
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-) = (28 ± 1.4 ± 0.5) keV or to the branching ratio B(ρ0→π+π-π+π-) = (1.8 ± 0.9 ± 0.3)·10-5. (C) 2000 Published by Elsevier Science B.V.