We are proud to announce the publication of the first physics results from the LEGEND-200 experiment in Physical Review Letters

(accepted September 29, 2025)

The paper, titled
“First Results on the Search for Lepton Number Violating Neutrinoless Double-Beta Decay with the LEGEND-200 Experiment”,
presents the initial data from the world’s most sensitive search for neutrinoless double-beta decay of ⁷⁶Ge.

LEGEND follows a staged approach. LEGEND-200, operating up to 200 kg of enriched germanium detectors immersed in liquid argon at the INFN Gran Sasso National Laboratory (LNGS), represents the first stage of the LEGEND scientific program. While LEGEND-200 will continue data taking toward a discovery sensitivity beyond 10²⁷ years, the next stage, LEGEND-1000, with a total detector mass of one ton of enriched germanium, is currently under preparation. The ultimate goal of the LEGEND program is to search for lepton-number violation and the Majorana nature of neutrinos with a discovery sensitivity beyond 10²⁸ years.

This first milestone of LEGEND-200 marks an important step toward answering one of the central questions of modern physics — whether neutrinos are their own antiparticles and how this relates to the origin of matter in the universe.

Read the accepted paper here:

Physical Review Letters – Accepted Paper

Large Enriched Germanium Experiment for Neutrinoless ββ Decay - LEGEND

The LEGEND collaboration is comprised of over 250 researchers from about 50 institutions from around the world, working together to develop the largest ⁷⁶Ge neutrinoless double-beta decay experiment in history. By combining the technological expertise and experience from the GERDA experiment and MAJORANA DEMONSTRATOR, LEGEND is expected to reach a design sensitivity two orders of magnitude greater than its predecessors.

The physics case

Majorana neutrinos

Since their discovery, neutrinos have been an object of extensive experimental study and the knowledge about their properties has advanced our understanding of weak interactions significantly. Still unanswered, however, is the very fundamental question whether the neutrino is identical to its anti-particle...

The physics case

Majorana neutrinos

Since their discovery, neutrinos have been an object of extensive experimental study and the knowledge about their properties has advanced our understanding of weak interactions significantly. Still unanswered, however, is the very fundamental question whether the neutrino is identical to its anti-particle...