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1811097833636364288
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MIT
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© 2019 authors. Published by the American Physical Society. We present a precision analysis of the Xe136 two-neutrino ββ electron spectrum above 0.8 MeV, based on high-statistics data obtained with the KamLAND-Zen experiment. An improved formalism for the two-neutrino ββ rate allows us to measure the ratio of the leading and subleading 2νββ nuclear matrix elements (NMEs), ζ312ν=-0.26-0.25+0.31. Theoretical predictions from the nuclear shell model and the majority of the quasiparticle random-phase approximation (QRPA) calculations are consistent with the experimental limit. However, part of the ζ312ν range allowed by the QRPA is excluded by the present measurement at the 90% confidence level. Our analysis reveals that predicted ζ312ν values are sensitive to the quenching of NMEs and the competing contributions from low- and high-energy states in the intermediate nucleus. Because these aspects are also at play in neutrinoless ββ decay, ζ312ν provides new insights toward reliable neutrinoless ββ NMEs.
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2024-09-23T17:05:41Z
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Article
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mit-1721.1/136196
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Massachusetts Institute of Technology
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English
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2024-09-23T17:05:41Z
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2021
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American Physical Society (APS)
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dspace
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mit-1721.1/1361962022-04-01T17:27:47Z Precision Analysis of the Xe 136 Two-Neutrino β β Spectrum in KamLAND-Zen and Its Impact on the Quenching of Nuclear Matrix Elements © 2019 authors. Published by the American Physical Society. We present a precision analysis of the Xe136 two-neutrino ββ electron spectrum above 0.8 MeV, based on high-statistics data obtained with the KamLAND-Zen experiment. An improved formalism for the two-neutrino ββ rate allows us to measure the ratio of the leading and subleading 2νββ nuclear matrix elements (NMEs), ζ312ν=-0.26-0.25+0.31. Theoretical predictions from the nuclear shell model and the majority of the quasiparticle random-phase approximation (QRPA) calculations are consistent with the experimental limit. However, part of the ζ312ν range allowed by the QRPA is excluded by the present measurement at the 90% confidence level. Our analysis reveals that predicted ζ312ν values are sensitive to the quenching of NMEs and the competing contributions from low- and high-energy states in the intermediate nucleus. Because these aspects are also at play in neutrinoless ββ decay, ζ312ν provides new insights toward reliable neutrinoless ββ NMEs. 2021-10-27T20:34:13Z 2021-10-27T20:34:13Z 2019 2020-11-18T14:52:19Z Article http://purl.org/eprint/type/JournalArticle https://hdl.handle.net/1721.1/136196 en 10.1103/PHYSREVLETT.122.192501 Physical Review Letters Creative Commons Attribution 4.0 International license https://creativecommons.org/licenses/by/4.0/ application/pdf American Physical Society (APS) APS
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| spellingShingle |
Precision Analysis of the Xe 136 Two-Neutrino β β Spectrum in KamLAND-Zen and Its Impact on the Quenching of Nuclear Matrix Elements
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| title |
Precision Analysis of the Xe 136 Two-Neutrino β β Spectrum in KamLAND-Zen and Its Impact on the Quenching of Nuclear Matrix Elements
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| title_full |
Precision Analysis of the Xe 136 Two-Neutrino β β Spectrum in KamLAND-Zen and Its Impact on the Quenching of Nuclear Matrix Elements
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| title_fullStr |
Precision Analysis of the Xe 136 Two-Neutrino β β Spectrum in KamLAND-Zen and Its Impact on the Quenching of Nuclear Matrix Elements
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| title_full_unstemmed |
Precision Analysis of the Xe 136 Two-Neutrino β β Spectrum in KamLAND-Zen and Its Impact on the Quenching of Nuclear Matrix Elements
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| title_short |
Precision Analysis of the Xe 136 Two-Neutrino β β Spectrum in KamLAND-Zen and Its Impact on the Quenching of Nuclear Matrix Elements
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| title_sort |
precision analysis of the xe 136 two neutrino β β spectrum in kamland zen and its impact on the quenching of nuclear matrix elements
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| url |
https://hdl.handle.net/1721.1/136196
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