Light, Unstable Sterile Neutrinos: Phenomenology, a Search in the IceCube Experiment, and a Global Picture
Longstanding anomalies in neutrino oscillation experiments point to the existence of a fourth, hypothetical neutrino: the sterile neutrino. Global fits to a sterile neutrino model find a strong preference for such a model over the massive neutrino Standard Model. However, the fit results suffer from...
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ftmit:oai:dspace.mit.edu:1721.1/142685 2023-06-11T04:16:48+02:00 Light, Unstable Sterile Neutrinos: Phenomenology, a Search in the IceCube Experiment, and a Global Picture Moulai, Marjon H. Conrad, Janet M. Massachusetts Institute of Technology. Department of Physics 2022-05-19T23:48:30.173Z application/pdf https://hdl.handle.net/1721.1/142685 unknown Massachusetts Institute of Technology https://hdl.handle.net/1721.1/142685 In Copyright - Educational Use Permitted Copyright MIT http://rightsstatements.org/page/InC-EDU/1.0/ Thesis 2022 ftmit 2023-05-29T08:19:46Z Longstanding anomalies in neutrino oscillation experiments point to the existence of a fourth, hypothetical neutrino: the sterile neutrino. Global fits to a sterile neutrino model find a strong preference for such a model over the massive neutrino Standard Model. However, the fit results suffer from inconsistencies between datasets, referred to as tension. This motivates more complicated models for new physics. This thesis considers a model of unstable sterile neutrinos, where the heaviest mass state can decay. First, the phenomenology of unstable sterile neutrinos is explored in the IceCube experiment, a gigaton neutrino detector located at the South Pole. Second, global fits to traditional and unstable sterile neutrino models are combined with one year of data from IceCube. A preference for the unstable sterile neutrino model is found, as well as a reduction in tension. Lastly, a high statistics search for unstable sterile neutrinos is performed in IceCube. The Standard Model is rejected with a ????-value of 2.8% and the traditional sterile neutrino model is rejected with a ????-value of 4.9%. The best-fit point is [formula] , [formula], and ????² = 2.5???? ± 1.5????, where ???? is the coupling that mediates the neutrino decay. The best-fit corresponds to a lifetime of the heaviest neutrino of ????₄/????₄ = 6 × 10⁻¹⁶ s/eV. A Bayesian analysis finds a best model with similar sterile parameters. Ph.D. Thesis South pole DSpace@MIT (Massachusetts Institute of Technology) South Pole |
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Longstanding anomalies in neutrino oscillation experiments point to the existence of a fourth, hypothetical neutrino: the sterile neutrino. Global fits to a sterile neutrino model find a strong preference for such a model over the massive neutrino Standard Model. However, the fit results suffer from inconsistencies between datasets, referred to as tension. This motivates more complicated models for new physics. This thesis considers a model of unstable sterile neutrinos, where the heaviest mass state can decay. First, the phenomenology of unstable sterile neutrinos is explored in the IceCube experiment, a gigaton neutrino detector located at the South Pole. Second, global fits to traditional and unstable sterile neutrino models are combined with one year of data from IceCube. A preference for the unstable sterile neutrino model is found, as well as a reduction in tension. Lastly, a high statistics search for unstable sterile neutrinos is performed in IceCube. The Standard Model is rejected with a ????-value of 2.8% and the traditional sterile neutrino model is rejected with a ????-value of 4.9%. The best-fit point is [formula] , [formula], and ????² = 2.5???? ± 1.5????, where ???? is the coupling that mediates the neutrino decay. The best-fit corresponds to a lifetime of the heaviest neutrino of ????₄/????₄ = 6 × 10⁻¹⁶ s/eV. A Bayesian analysis finds a best model with similar sterile parameters. Ph.D. |
author2 |
Conrad, Janet M. Massachusetts Institute of Technology. Department of Physics |
format |
Thesis |
author |
Moulai, Marjon H. |
spellingShingle |
Moulai, Marjon H. Light, Unstable Sterile Neutrinos: Phenomenology, a Search in the IceCube Experiment, and a Global Picture |
author_facet |
Moulai, Marjon H. |
author_sort |
Moulai, Marjon H. |
title |
Light, Unstable Sterile Neutrinos: Phenomenology, a Search in the IceCube Experiment, and a Global Picture |
title_short |
Light, Unstable Sterile Neutrinos: Phenomenology, a Search in the IceCube Experiment, and a Global Picture |
title_full |
Light, Unstable Sterile Neutrinos: Phenomenology, a Search in the IceCube Experiment, and a Global Picture |
title_fullStr |
Light, Unstable Sterile Neutrinos: Phenomenology, a Search in the IceCube Experiment, and a Global Picture |
title_full_unstemmed |
Light, Unstable Sterile Neutrinos: Phenomenology, a Search in the IceCube Experiment, and a Global Picture |
title_sort |
light, unstable sterile neutrinos: phenomenology, a search in the icecube experiment, and a global picture |
publisher |
Massachusetts Institute of Technology |
publishDate |
2022 |
url |
https://hdl.handle.net/1721.1/142685 |
geographic |
South Pole |
geographic_facet |
South Pole |
genre |
South pole |
genre_facet |
South pole |
op_relation |
https://hdl.handle.net/1721.1/142685 |
op_rights |
In Copyright - Educational Use Permitted Copyright MIT http://rightsstatements.org/page/InC-EDU/1.0/ |
_version_ |
1768375407788163072 |