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Pseudoscalar-pole contributions to Hadronic Light-by-Light scattering in the muon g − 2 from twisted mass lattice QCD

Burri, Sebastian Andreas (2023). Pseudoscalar-pole contributions to Hadronic Light-by-Light scattering in the muon g − 2 from twisted mass lattice QCD. (Thesis). Universität Bern, Bern

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Abstract

The anomalous magnetic moment of the muon provides one of the most stringent tests of the Standard Model with very precise determinations from both experiments and theory. However, there is a persistent tension between the two determinations, which has increased to 4.2 standard deviations with the latest experimental result. Currently, experimental efforts are underway to reduce the uncertainty by up to a factor of four. Testing the Standard Model on this more precise level requires that also the theory error is reduced to the same level. The Standard Model uncertainty is dominated by low-energy contributions from the strong interaction, namely the Hadronic Vacuum Polarization and the Hadronic Light-by-Light scattering. The Hadronic Light-by-Light scattering can be systematically decomposed into contributions from various intermediate states, with the dominant role played by the π⁰-pole, followed by the η- and η′-poles. In this work, the π⁰- and η-pole contributions are estimated from twisted mass lattice QCD with physical light and heavy quark masses. Three ensembles generated by the Extended Twisted Mass Collaboration are used for the π⁰- and one ensemble for the η-pole calculation. For the η-pole, this is the first ab-initio calculation directly at the physical point. The main results are 56.7(3.1) × 10⁻¹¹ for the π⁰-pole contribution and 13.8(5.5) × 10⁻¹¹ for the η-pole contribution.

Item Type: Thesis
Dissertation Type: Cumulative
Date of Defense: 30 August 2023
Subjects: 500 Science > 530 Physics
Institute / Center: 08 Faculty of Science > Institute of Theoretical Physics
Depositing User: Hammer Igor
Date Deposited: 11 Sep 2023 14:26
Last Modified: 11 Sep 2023 15:43
URI: https://boristheses.unibe.ch/id/eprint/4515

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