Noël, Frederic (2024). μ → e conversion in nuclei: EFT description, charge densities, and pseudo-scalar decays. (Thesis). Universität Bern, Bern
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Abstract
The description of LFV μ → e conversion in nuclei proves challenging due to the various energy scales involved, ranging from the BSM scale via chiral scales down all the way to nuclear and bound-state physics scales. Nevertheless, this is a pressing matter in light of the upcoming experiments Mu2e and COMET, which will improve the experimental limits by four orders of magnitude. This can be done in a model-independent way using an effective field theory framework in terms of effective BSM operators, which however crucially depends on hadronic and nuclear matrix elements. In this work, we present the comprehensive EFT formalism we developed, which describes bound-state physics and nuclear responses at the same time, and discuss the related hadronic and nuclear uncertainties. In particular, the uncertainties inherent in these non-perturbative inputs limit the discriminating power among different BSM scenarios that can be achieved. In order to quantify the associated uncertainties, we revisit nuclear charge densities and propagate uncertainties from elastic electron scattering experiments. These charge densities, parameterized in terms of Fourier-Bessel series, are crucial ingredients, in combination with EFT and nuclear-structure techniques, for the evaluation of general μ → e conversion rates with quantified uncertainties. Using this framework, we could also transfer the very strong experimental limits for μ → e conversion onto LFV decays of light pseudo-scalars, resulting in indirect limits surpassing the direct experimental ones by several orders of magnitude.
| Item Type: | Thesis |
|---|---|
| Dissertation Type: | Single |
| Date of Defense: | 18 September 2024 |
| Subjects: | 500 Science > 530 Physics |
| Institute / Center: | 08 Faculty of Science > Institute of Theoretical Physics 10 Strategic Research Centers > Albert Einstein Center for Fundamental Physics (AEC) |
| Depositing User: | Hammer Igor |
| Date Deposited: | 07 Oct 2024 16:04 |
| Last Modified: | 07 Oct 2024 16:04 |
| URI: | https://boristheses.unibe.ch/id/eprint/5476 |
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