Phenomenological Estimate of Isospin Breaking in Hadronic Vacuum Polarization.

Hoferichter, Martin; Colangelo, Gilberto; Hoid, Bai-Long; Kubis, Bastian; Ruiz de Elvira, Jacobo; Schuh, Dominic; Stamen, Dominik; Stoffer, Peter (2023). Phenomenological Estimate of Isospin Breaking in Hadronic Vacuum Polarization. Physical review letters, 131(16), p. 161905. American Physical Society 10.1103/PhysRevLett.131.161905

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Puzzles in the determination of the hadronic-vacuum-polarization contribution currently impede a conclusive interpretation of the precision measurement of the anomalous magnetic moment of the muon at the Fermilab experiment. One such puzzle concerns tensions between evaluations in lattice QCD and using e^{+}e^{-}→hadrons cross-section data. In lattice QCD, the dominant isospin-symmetric part and isospin-breaking (IB) corrections are calculated separately, with very different systematic effects. Identifying these two pieces in a data-driven approach provides an opportunity to compare them individually and trace back the source of the discrepancy. Here, we estimate the IB component of the lattice-QCD calculations from phenomenology, based on a comprehensive study of exclusive contributions that can be enhanced via infrared singularities, threshold effects, or hadronic resonances, including, for the first time, in the e^{+}e^{-}→3π channel. We observe sizable cancellations among different channels, with a sum that even suggests a slightly larger result for the QED correction than obtained in lattice QCD. We conclude that the tensions between lattice QCD and e^{+}e^{-} data therefore cannot be explained by the IB contributions in the lattice-QCD calculations.

Item Type:

Journal Article (Original Article)

Division/Institute:

10 Strategic Research Centers > Albert Einstein Center for Fundamental Physics (AEC)
08 Faculty of Science > Institute of Theoretical Physics

UniBE Contributor:

Hoferichter, Martin, Colangelo, Gilberto

Subjects:

500 Science > 530 Physics

ISSN:

0031-9007

Publisher:

American Physical Society

Language:

English

Submitter:

Pubmed Import

Date Deposited:

06 Nov 2023 14:53

Last Modified:

12 Nov 2023 02:34

Publisher DOI:

10.1103/PhysRevLett.131.161905

PubMed ID:

37925732

BORIS DOI:

10.48350/188588

URI:

https://boris.unibe.ch/id/eprint/188588

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