Search for lepton flavor-violating decay modes B0→ K*0τ±ℓ∓ (ℓ = e, μ) with hadronic B-tagging at Belle and Belle II

I Adachi; Y Ahn; H Aihara; N Akopov; S Alghamdi; M Alhakami; A Aloisio; K Amos; M Angelsmark; N Anh Ky; C Antonioli; DM Asner; H Atmacan; V Aushev; M Aversano; R Ayad; V Babu; H Bae; NK Baghel; S Bahinipati; P Bambade; S Banerjee; S Bansal; M Barrett; J Baudot; A Baur; A Beaubien; F Becherer; J Becker; JV Bennett; FU Bernlochner; V Bertacchi; M Bertemes; E Bertholet; M Bessner; S Bettarini; B Bhuyan; F Bianchi; T Bilka; D Biswas; A Bobrov; D Bodrov; J Borah; A Boschetti; A Bozek; M Bračko; P Branchini; RA Briere; TE Browder; A Budano; S Bussino; M Campajola; L Cao; G Casarosa; C Cecchi; MC Chang; P Cheema; BG Cheon; K Chilikin; J Chin; HE Cho; K Cho; SJ Cho; SK Choi; S Choudhury; I Consigny; L Corona; JX Cui; E De La Cruz-Burelo; SA De La Motte; G de Marino; G De Pietro; R de Sangro; M Destefanis; A Di Canto; J Dingfelder; Z Doležal; I Domínguez Jiménez; TV Dong; X Dong; M Dorigo; G Dujany; P Ecker; D Epifanov; R Farkas; P Feichtinger; T Ferber; T Fillinger; C Finck; G Finocchiaro; F Forti; A Frey; BG Fulsom; A Gale; E Ganiev; M Garcia-Hernandez; R Garg; G Gaudino; V Gaur; V Gautam

Journal article

Search for lepton flavor-violating decay modes B0→ K*0τ±ℓ∓ (ℓ = e, μ) with hadronic B-tagging at Belle and Belle II

I Adachi, Y Ahn, H Aihara, N Akopov, S Alghamdi, M Alhakami, A Aloisio, K Amos, M Angelsmark, N Anh Ky, C Antonioli, DM Asner, H Atmacan, V Aushev, M Aversano, R Ayad, V Babu, H Bae, NK Baghel, S Bahinipati Show all

Journal of High Energy Physics | Springer Science and Business Media LLC | Published : 2025

DOI: 10.1007/JHEP08(2025)184

Abstract

We present the results of a search for the charged-lepton-flavor violating decays B0 → K*0τ±ℓ∓, where ℓ∓ is either an electron or a muon. The results are based on 365 fb−1 and 711 fb−1 datasets collected with the Belle II and Belle detectors, respectively. We use an exclusive hadronic B-tagging technique, and search for a signal decay in the system recoiling against a fully reconstructed B meson. We find no evidence for B0 → K*0τ±ℓ∓ decays and set upper limits on the branching fractions in the range of (2.9–6.4)×10−5 at 90% confidence level.