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

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.