We present the results of a search for charged-lepton-flavor violating decays, where ℓ− is either an electron or a muon. We combine e+e− data samples recorded by the Belle II experiment at the SuperKEKB collider (428 fb−1) with samples recorded by the Belle experiment at the KEKB collider (980 fb−1) to obtain a sample of 1.3 billion e+e− → τ+τ− events. We observe 0 and 1 events and set 90% confidence level upper limits of 0.8 × 10−8 and 1.2 × 10−8 on the branching fractions of the decay modes and, respectively. These are the most stringent upper limits to date.
Adachi, I., Aggarwal, L., Ahmed, H., Ahn, Y., Aihara, H., Akopov, N., et al. (2025). Search for lepton-flavor-violating $${\tau }^{-}\to {{\ell}}^{-}{K}_{s}^{0}$$ decays at Belle and Belle II. JOURNAL OF HIGH ENERGY PHYSICS, 2025(8), 092-0-092-26 [10.1007/jhep08(2025)092].
Search for lepton-flavor-violating $${\tau }^{-}\to {{\ell}}^{-}{K}_{s}^{0}$$ decays at Belle and Belle II
Branchini, P.Membro del Collaboration Group
;Budano, A.Membro del Collaboration Group
;Bussino, S.Membro del Collaboration Group
;De Pietro, G.Membro del Collaboration Group
;Laurenza, M.Membro del Collaboration Group
;Martellini, C.Membro del Collaboration Group
;Martini, A.Membro del Collaboration Group
;
2025-01-01
Abstract
We present the results of a search for charged-lepton-flavor violating decays, where ℓ− is either an electron or a muon. We combine e+e− data samples recorded by the Belle II experiment at the SuperKEKB collider (428 fb−1) with samples recorded by the Belle experiment at the KEKB collider (980 fb−1) to obtain a sample of 1.3 billion e+e− → τ+τ− events. We observe 0 and 1 events and set 90% confidence level upper limits of 0.8 × 10−8 and 1.2 × 10−8 on the branching fractions of the decay modes and, respectively. These are the most stringent upper limits to date.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
