Study of the reactions $e^+e^-\toπ^+π^-π^0π^0π^0γ$ and $π^+π^-π^0π^0ηγ$ at center-of-mass energies from threshold to 4.35 GeV using initial-state radiation

Abstract

We study the processes $e^+e^-\toπ^+π^-π^0π^0π^0γ$ and $π^+π^-π^0π^0ηγ$ in which an energetic photon is radiated from the initial state. The data were collected with the BaBar~ detector at SLAC. About 14\,000 and 4700 events, respectively, are selected from a data sample corresponding to an integrated luminosity of 469~$fb^{-1}$. The invariant mass of the hadronic final state defines the effective $e^+e^-$ center-of-mass energy. From the mass spectra, the first precise measurement of the $e^+e^-\toπ^+π^-π^0π^0π^0$ cross section and the first measurement ever of the $e^+e^-\toπ^+π^-π^0π^0η$ cross section are performed. The center-of-mass energies range from threshold to 4.35~GeV. The systematic uncertainty is typically between 10 and 13\%. The contributions from $ωπ^0π^0$, $ηπ^+π^-$, and other intermediate states are presented. We observe the $J/ψ$ and $ψ(2S)$ in most of these final states and measure the corresponding branching fractions, many of them for the first time.