Electroweak radiative corrections in super-allowed beta decays from Ab initio theory
| dc.contributor.author | Gennari, Michael | |
| dc.contributor.supervisor | Navratil, Petr | |
| dc.contributor.supervisor | Kowalewski, Robert | |
| dc.date.accessioned | 2025-08-15T22:08:58Z | |
| dc.date.available | 2025-08-15T22:08:58Z | |
| dc.date.issued | 2025 | |
| dc.degree.department | Department of Physics and Astronomy | |
| dc.degree.level | Doctor of Philosophy PhD | |
| dc.description.abstract | A systematically improvable, ab initio model is developed to compute nuclear-structure-dependent elec troweak radiative corrections in superallowed Fermi β decays. With inter-nucleon interactions derived from the low-energy symmetries of quantum chromo-dynamics via a prescription of effective field theory, the nuclear many-body configurations are obtained in the quasi-exact, no-core shell model. This approach rigorously treats all nucleons as active degrees of freedom in solution of the non-relativistic, many-body Schrödinger equation with Hamiltonian constructed from chiral effective field theory. One of the two key nuclear-structure corrections to superallowed β decays, known as δNS, arises from modifications to the one-nucleon γW box diagram when immersed in the nuclear medium. It is computed for the two lightest superallowed transitions: the 10C → 10B and 14O → 14N transitions. The nuclear γW box amplitude is itself explicitly evaluated as the time-ordered product of the electromagnetic and charge-changing weak current operators, providing a transparent multipole decomposition of the currents. The resulting complicated amplitude structure involves many-body resolvent operators which are treated with the Lanczos strengths method, the key tool of this dissertation. As much as is permitted by the Lanczos algorithm, this method incorporates quasi-exact information about the complete intermediate nuclear spectrum. For 10C → 10B, we find the nuclear-structure-dependent radiative correction δNS to be δNS [10C → 10B] = −0.422 (14) PME (4)Ω(9)χ(24)sh(12)n,el % , which represents a 1.6x reduction in the quoted uncertainty compared to prior literature estimates despite the accounting for additional uncertainties. Preliminary results for the 14O → 14N transition indicate a markedly different distribution of the amplitude strengths, reflecting a strong Gamow-Teller suppression and highlighting the need for higher-multipole analysis before a final value is quoted. These precision gains directly impact the determination of Vud and thus the top-row, Cabibbo Kobayashi-Maskawa matrix unitarity test, motivating renewed experimental efforts– particularly a more precise measurement of the 10C branching ratio– and opening the way to analogous, precision ab initio studies for other electroweak processes in light nuclei. | |
| dc.description.scholarlevel | Graduate | |
| dc.identifier.bibliographicCitation | Gennari, M., Drissi, M., Gorchtein, M., Navrátil, P., & Seng, C. Y. (2025). Ab Initio Strategy for Taming the Nuclear-Structure Dependence of V ud Extractions: The C 10→ B 10 Superallowed Transition. Physical Review Letters, 134(1), 012501. DOI: https://doi.org/10.1103/PhysRevLett.134.012501 | |
| dc.identifier.uri | https://hdl.handle.net/1828/22619 | |
| dc.language | English | eng |
| dc.language.iso | en | |
| dc.rights | Available to the World Wide Web | |
| dc.subject | nuclear theory | |
| dc.subject | many-body theory | |
| dc.subject | electroweak physics | |
| dc.title | Electroweak radiative corrections in super-allowed beta decays from Ab initio theory | |
| dc.type | Thesis |