Measurement of the e+e−→ΛΛ¯ cross section from threshold to 3.00 GeV using events with initial-state radiation

Physics and Astronomy (miscellaneous) Atomic 530 7. Clean energy 01 natural sciences High Energy Physics - Experiment MAGNETIC-MOMENT; TAGGED PHOTONS; STORAGE-RING; FINAL-STATES; MONTE-CARLO; ANNIHILATION; DETECTOR; COLLISIONS Particle and Plasma Physics 0103 physical sciences Nuclear FINAL-STATES; MONTE-CARLO; DETECTOR; COLLISIONS; SDG 7 - Affordable and Clean Energy Quantum Physics Molecular HEP; BaBar Particle and High Energy Physics Nuclear and Plasma Physics Nuclear & Particles Physics Mathematical physics Physical Sciences Astronomical sciences BaBar PEP-II Initial state radiation Physics and Astronomy (miscellaneous); BaBar; PEP-II; Initial state radiation; Astronomical and Space Sciences
DOI: 10.1103/physrevd.107.072005 Publication Date: 2023-04-18T15:56:53Z
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ABSTRACT
We report a measurement of the e+e−→π+π−π0 cross section in the energy range from 0.62 to 3.50 GeV using an initial-state radiation technique. We use an e+e− data sample corresponding to 191  fb−1 of integrated luminosity, collected at a center-of-mass energy at or near the ϒ(4S) resonance with the Belle II detector at the SuperKEKB collider. Signal yields are extracted by fitting the two-photon mass distribution in e+e−→π+π−π0γ events, which involve a π0→γγ decay and an energetic photon radiated from the initial state. Signal efficiency corrections with an accuracy of 1.6% are obtained from several control data samples. The uncertainty on the cross section at the ω and ϕ resonances is dominated by the systematic uncertainty of 2.2%. The resulting cross sections in the 0.62–1.80 GeV energy range yield aμ3π=[48.91±0.23(stat)±1.07(syst)]×10−10 for the leading-order hadronic vacuum polarization contribution to the muon anomalous magnetic moment. This result differs by 2.5 standard deviations from the most precise current determination. Published by the American Physical Society 2024
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