Abstract
We study the processes e+e−→π+π−π0π0π0π0γ and π+π−π0π0π0ηγ in which an energetic photon is radiated from the initial state. The data were collected with the BABAR detector at the SLAC National Accelerator Laboratory. About 7300 and 870 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−→π+π−π0π0π0π0 and the e+e−→π+π−π0π0π0η cross sections are performed. The contributions from ωπ0π0π0, ηπ+π−π0, ωη, 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.20 MoreReceived 4 October 2021Accepted 16 November 2021DOI:https://doi.org/10.1103/PhysRevD.104.112004Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasParticle interactionsTechniquesParticle productionParticles & Fields
Highlights
Many precision Standard Model (SM) predictions require the hadronic vacuum polarization (HVP) terms to be taken into account
This paper reports on analyses of the πþπ−4π0 and πþπ−3π0η final states produced in conjunction with an energetic photon, assumed to result from ISR
To evaluate the detector acceptance and efficiency, we have developed a special package of Monte Carlo (MC) simulation programs for radiative processes based on the approach of Czyż and Kühn [25]
Summary
Many precision Standard Model (SM) predictions require the hadronic vacuum polarization (HVP) terms to be taken into account. In the energy region from the hadronic threshold to about 2 GeV, the inclusive hadronic cross section cannot be measured or calculated reliably, and a sum of exclusive states must be used. It is important for the calculation of the muon anomalous magnetic moment (gμ − 2), which is most sensitive to the low-energy region. Electron-positron annihilation events with initial-state radiation (ISR) can be used to study processes over a wide range of energies below the nominal eþe− c.m. energy (Ec:m:), as proposed in Ref. A clear J=ψ signal is observed for both the πþπ−4π0 and πþπ−3π0η channels, and the corresponding J=ψ branching fractions are measured
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