Hoferichter, Martin; Hoid, Bai-Long; Kubis, Bastian; Schuh, Dominic (2023). Isospin-breaking effects in the three-pion contribution to hadronic vacuum polarization. Journal of High Energy Physics, 2023(8) Springer 10.1007/JHEP08(2023)208
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Isospin-breaking (IB) effects are required for an evaluation of hadronic vacuum
polarization at subpercent precision. While the dominant contributions arise from the
e+e− → π+π− channel, also IB in the subleading channels can become relevant for a detailed understanding, e.g., of the comparison to lattice QCD. Here, we provide such an analysis for e+e− → 3π by extending our dispersive description of the process, including estimates of final-state radiation (FSR) and ρ–ω mixing. In particular, we develop a formalism to capture the leading infrared-enhanced effects in terms of a correction factor η3π that generalizes the analog treatment of virtual and final-state photons in the 2π case. The
global fit to the e+e− → 3π data base, subject to constraints from analyticity, unitarity,
and the chiral anomaly, gives a3π | = 45.91(53) × 10−10 for the total 3π contribution μ ≤1.8GeV to the anomalous magnetic moment of the muon, of which aFSR[3π] = 0.51(1) × 10−10 and μ aρ–ω[3π] = −2.68(70)×10−10 can be ascribed to IB. We argue that the resulting cancellation μ with ρ–ω mixing in e+e− → 2π can be understood from a narrow-resonance picture, and provide updated values for the vacuum-polarization-subtracted vector-meson parameters Mω = 782.70(3) MeV, Mφ = 1019.21(2) MeV, Γω = 8.71(3) MeV, and Γφ = 4.27(1) MeV.
Item Type: |
Journal Article (Original Article) |
|---|---|
Division/Institute: |
08 Faculty of Science > Institute of Theoretical Physics 10 Strategic Research Centers > Albert Einstein Center for Fundamental Physics (AEC) |
UniBE Contributor: |
Hoferichter, Martin |
Subjects: |
500 Science > 530 Physics 500 Science |
ISSN: |
1029-8479 |
Publisher: |
Springer |
Language: |
English |
Submitter: |
Franziska Stämpfli |
Date Deposited: |
04 Dec 2023 12:27 |
Last Modified: |
04 Dec 2023 12:27 |
Publisher DOI: |
10.1007/JHEP08(2023)208 |
ArXiv ID: |
2307.02546 |
BORIS DOI: |
10.48350/189709 |
URI: |
https://boris.unibe.ch/id/eprint/189709 |
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