Search for the lepton number violating process * * This work is supported in part by National Key R&D Program of China under Contracts Nos. 2023YFA1606000, 2023YFA1606704; National Natural Science Foundation of China (NSFC) under Contracts Nos. 12035009, 11635010, 11935015, 11935016, 11935018, 12025502, 12035013, 12061131003, 12192260, 12192261, 12192262, 12192263, 12192264, 12192265, 12221005, 12225509, 12235017, 12361141819; the Chinese Academy of Sciences (CAS) Large-Scale Scientific Facility Program; CAS under Contract No. YSBR-101; 100 Talents Program of CAS; The Institute of Nuclear and Particle Physics (INPAC) and Shanghai Key Laboratory for Particle Physics and Cosmology; German Research Foundation DFG under Contract No. FOR5327; Istituto Nazionale di Fisica Nucleare, Italy; Knut and Alice Wallenberg Foundation under Contracts Nos. 2021.0174, 2021.0299; Ministry of Development of Turkey under Contract No. DPT2006K-120470; National Research Foundation of Korea under Contract No. NRF-2022R1A2C1092335; National Science and Technology fund of Mongolia; National Science Research and Innovation Fund (NSRF) via the Program Management Unit for Human Resources & Institutional Development, Research and Innovation of Thailand under Contract No. B50G670107; Polish National Science Centre under Contract No. 2024/53/B/ST2/00975; Swedish Research Council under Contract No. 2019.04595; U. S. Department of Energy under Contract No. DE-FG02-05ER41374

Journal article

Based on events collected with the BESIII detector, we search for the lepton number violating decay for the first time. The upper limit on the branching fraction of this decay is set to at the 90% confidence level with a frequentist method. This is the first search for decays with a lepton number change by two, offering valuable insights into the underlying physical processes.

Authors: Ablikim, M; Achasov, MN; Adlarson, P; Ai, XC; Aliberti, R

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: IOP Publishing
• Journal: Chinese Physics C
• Volume: 50
• Issue: 1
• Article number: 013107
• Publication date: 2026-01-01
• DOI: 10.1088/1674-1137/ae0f86
• ISSN: 1674-1137
• Language: English
• Keywords: Lepton number violation; neutrinoless double beta decay; matter anti-matter asymmetry