Study of the reactions e⁺e⁻ → 2(π⁺π⁻)π⁰π⁰π⁰ and 2(π⁺π⁻)π⁰π⁰η at center-of-mass energies from threshold to 4.5 GeV using initial-state radiation

Abstract

We study the processes e⁺e⁻ → 2(π⁺π⁻)π⁰π⁰π⁰γ and 2(π⁺π⁻)π⁰π⁰ηγ 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. The center-of-mass energies range from threshold to 4.5 GeV. From the mass spectra, the first ever measurements of the e⁺e⁻ → 2(π⁺π⁻)π⁰π⁰π⁰ and the e⁺e⁻ → 2(π⁺π−)π⁰π⁰η cross sections are performed. The contributions from ωπ⁺π−π⁰π⁰, η2(π⁺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.

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