Neutrinoless double-beta decay search with the LEGEND experiment

Neutrinoless double-beta decay is a nuclear decay, given as (A,Z) → (A,Z + 2) +2e -, with deep consequences for the understanding of our universe. A strong experimental program is underway to search for this transition with many proposed experiments using different technologies. In this article the LEGEND experiment, which uses 76Ge as the isotope of interest, will be described. We will discuss both the first stage, LEGEND-200, which is now taking data at the Laboratori Nazionali del Gran Sasso of INFN in Italy, and the future stage, LEGEND-1000. LEGEND-200 has analyzed a first sample of data (48.3 kg·yr) collected from March 2023 to February 2024 with a background index not far away from its goal of 2×10-4 cnts/(keV·kg·yr). Combining the LEGEND-200 data with those of Gerda and Majorana Demonstrator one obtains a sensitivity on the half-life of 0νββ decay in 76Ge of T 1/2 > 2.8 × 1026 yr at 90% C.L. and a limit on T 1/2 > 1.9 × 1026 yr at 90% C.L.