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

TL;DR

This study measures the cross section of the process e+e- to four pions in the 920-1060 MeV range, revealing interference effects and determining the rare decay branching fraction of phi to four pions.

Contribution

It provides the first measurement of the e+e- to four-pion cross section in this energy range and extracts the phi decay branching ratio to four pions.

Findings

Measured cross section with interference pattern observed.

Determined the branching fraction BR(phi→π+π-π+π-) = (6.5±2.7±1.6)×10^{-6}.

Collected 6798±93 signal events from 9.8 pb^{-1} data.

Abstract

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): $\BR(\phi\to\pipi\pipi) = (6.5\pm2.7\pm1.6)\times 10^{-6}$.