First Results on the Search for Lepton Number Violating Neutrinoless Double-β Decay with the LEGEND-200 Experiment

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

  • LEGEND Collaboration - (Author)
  • Chair of Nuclear Physics
  • Chair of Accelerator Mass Spectrometry and Isotope Research (with HZDR)
  • University of North Carolina at Chapel Hill
  • Triangle Universities Nuclear Laboratory
  • Max Planck Institute for Nuclear Physics
  • University College London
  • Simon Fraser University
  • University of Zurich
  • University of South Carolina
  • Oak Ridge National Laboratory
  • University of Texas at Austin
  • Russian Research Centre Kurchatov Institute
  • National Institute for Nuclear Physics
  • Duke University
  • Roma Tre University
  • RAS - Institute for Nuclear Research
  • Gran Sasso Science Institute
  • North Carolina State University
  • University of Washington
  • Polytechnic University of Milan
  • University of Liverpool (UOL)
  • University of Padua
  • University of Milan - Bicocca
  • University of Milan
  • Lawrence Berkeley National Laboratory
  • South Dakota School of Mines & Technology
  • Leibniz Institute of Polymer Research Dresden

Abstract

The LEGEND Collaboration is searching for neutrinoless double-beta ((Formula presented)) decay by operating high-purity germanium detectors enriched in (Formula presented) 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 (Formula presented) 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 (Formula presented) in the (Formula presented) 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 (Formula presented) on the half-life of (Formula presented) decay, reveals no evidence for a signal and sets a new observed lower limit at (Formula presented) (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 (Formula presented), depending on the adopted nuclear matrix element.

Details

Original languageEnglish
Article number022701
Number of pages10
JournalPhysical review letters
Volume136
Issue number2
Publication statusPublished - 16 Jan 2026
Peer-reviewedYes

External IDs

PubMed 41616370
ORCID /0000-0002-0406-5800/work/206633980
ORCID /0000-0002-6705-7138/work/206635825

Keywords

ASJC Scopus subject areas