Study of the Process $e^+e^-\to \pi^+\pi^-\pi^+\pi^-$ IN THE C.M. Energy   Range 920--1060 MeV with the CMD-3 Detector
  A cross section of the process $e^+e^- \to \pipi\pipi$ has been measured using 6798$\pm$93 signal events from a data sample corresponding to an integrated luminosity of 9.8 pb$^{-1}$ collected with the CMD-3 detector in the center-of-mass energy range 920--1060 MeV. The measured cross section exhibits an interference pattern of the $\phi(1020)\to\pipi\pipi$ decay with a non-resonant process $e^+e^- \to \pipi\pipi$, from which we obtain the branching fraction of the doubly suppressed decays (by G-parity and OZI rule): $\BR(\phi\to\pipi\pipi) = (6.5\pm2.7\pm1.6)\times 10^{-6}$. 
R.R.Akhmetshin, A.N.Amirkhanov, A.V.Anisenkov, V.M.Aulchenko,   V.Sh.Banzarov, N.S.Bashtovoy, D.E.Berkaev, A.E.Bondar, A.V.B...
hep-ex