20.500.12556/DiRROS-29169 Search for lepton-flavor-violating ▫$\tau^- \to \mu^- \mu^+ \mu^-$▫ decays at Belle II We present the result of a search for the charged-lepton-flavor violating decay τ− → μ−μ+μ− using a 424 fb−1 sample of data recorded by the Belle II experiment at the SuperKEKB e+e− collider. The selection of e+e− → τ+τ− events is based on an inclusive reconstruction of the non-signal tau decay, and on a boosted decision tree to suppress background. We observe one signal candidate, which is compatible with the expectation from background processes. We set a 90% confidence level upper limit of 1.9 × 10−8 on the branching fraction of the τ− → μ−μ+μ− decay, which is the most stringent bound to date. flavour physics tau physics e+-e− Experiments fizika okusov tau fizika e+e- eksperimenti true false true SISSA Italija Angleški jezik Slovenski jezik © The Authors. Neznano 2026-04-22 14:37:14 2026-04-22 14:37:14 2026-04-23 04:02:16 0000-00-00 00:00:00 2024 0 0 Nasl. z nasl. zaslona; Opis vira z dne 31. 3. 2026; Avtorji iz Slovenije: Jyotirmoi Borah, Marko Bračko, Paul Feichtinger, Eldar Ganiev, Samo Korpar, Peter Križan, Manca Mrvar, Rok Pestotnik, Tomaž Podobnik, Marko Starič, Luka Šantelj, Valentina I. Zhukova; str. 1-19 Vol. 2024, article no. 62 Sep. 2024 0000-00-00 Zaloznikova Objavljeno NiDoloceno 2024-05-15 2024-07-31 2024-09-11 539 1029-8479 10.1007/JHEP09(2024)062 273762819 https://link.springer.com/article/10.1007/JHEP09(2024)062 1 023c7508-3e48-11f1-a343-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=43599 RAZ_Adachi_Ichiro_2024.pdf RAZ_Adachi_Ichiro_2024.pdf 1 29CE0EE3D1B7ADC5308D6389016586F1 f9bf5f7259cbd6e54ca07447569da637720ebb67e4cea05a5214c223b98f959e 7d2ca740-3e48-11f1-a343-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=43601 Institut Jožef Stefan 0 0 0