Document Type
Article
Abstract
The LEGEND Collaboration is searching for neutrinoless double-beta (0νββ) decay by operating high-purity germanium detectors enriched in 76Ge in a low-background liquid argon environment. Building on key technological innovations from the GERmanium Detector Array (GERDA) experiment and the MAJORANA DEMONSTRATOR experiment, LEGEND-200 has performed a first 0νββ decay search based on 61.0 kg yr of data. Over half of this exposure comes from our highest performing detectors, including newly developed inverted-coaxial detectors, and is characterized by an estimated background level of 0.5+0.3−0.2 cts/(keV ton yr) in the 0νββ decay signal region. A combined analysis of data from GERDA, the MAJORANA DEMONSTRATOR, and LEGEND-200, characterized by a 90% confidence level exclusion sensitivity of 2.8 × 1026 yr on the half-life of 0νββ decay, reveals no evidence for a signal and sets a new observed lower limit at T0ν1/2 > 1.9 × 1026 yr (90% confidence level). Assuming the decay is mediated by Majorana neutrinos, this corresponds to an upper limit on the effective Majorana mass in the range mββ < 75–200 meV, depending on the adopted nuclear matrix element.
Digital Object Identifier (DOI)
Publication Info
Published in Physical Review Letters, Volume 136, Issue 2, 2026.
Rights
©2026 American Physical Society. All rights reserved. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3 .
APA Citation
LEGEND Collaboration. (2026). First results on the search for lepton number violating neutrinoless double-β decay with the LEGEND-200 experiment. Physical Review Letters, 136(2), 022701. https://doi.org/10.1103/25tk-nctn