Search for Majorana Neutrinos Near the Inverted Mass Hierarchy Region with KamLAND-Zen.
Phys Rev Lett
; 117(8): 082503, 2016 Aug 19.
Article
em En
| MEDLINE
| ID: mdl-27588852
ABSTRACT
We present an improved search for neutrinoless double-beta (0νßß) decay of ^{136}Xe in the KamLAND-Zen experiment. Owing to purification of the xenon-loaded liquid scintillator, we achieved a significant reduction of the ^{110m}Ag contaminant identified in previous searches. Combining the results from the first and second phase, we obtain a lower limit for the 0νßß decay half-life of T_{1/2}^{0ν}>1.07×10^{26} yr at 90% C.L., an almost sixfold improvement over previous limits. Using commonly adopted nuclear matrix element calculations, the corresponding upper limits on the effective Majorana neutrino mass are in the range 61-165 meV. For the most optimistic nuclear matrix elements, this limit reaches the bottom of the quasidegenerate neutrino mass region.
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MEDLINE
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En
Ano de publicação:
2016
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Article