Measurement of B → τ ντ branching fraction with a hadronic tagging method at Belle II

I Adachi; K Adamczyk; H Ahmed; Y Ahn; H Aihara; N Akopov; M Alhakami; A Aloisio; N Althubiti; M Angelsmark; NA Ky; DM Asner; H Atmacan; V Aushev; M Aversano; R Ayad; V Babu; NK Baghel; S Bahinipati; P Bambade; S Banerjee; M Bartl; J Baudot; A Baur; A Beaubien; F Becherer; J Becker; JV Bennett; FU Bernlochner; V Bertacchi; E Bertholet; M Bessner; S Bettarini; B Bhuyan; F Bianchi; D Biswas; A Bobrov; D Bodrov; A Bondar; J Borah; A Boschetti; A Bozek; M Bračko; P Branchini; RA Briere; TE Browder; A Budano; S Bussino; Q Campagna; M Campajola; L Cao; G Casarosa; C Cecchi; MC Chang; P Cheema; BG Cheon; K Chilikin; K Chirapatpimol; HE Cho; K Cho; SJ Cho; SK Choi; S Choudhury; J Cochran; L Corona; JX Cui; E De La Cruz-Burelo; SA De La Motte; G De Nardo; G De Pietro; R de Sangro; M Destefanis; S Dey; A Di Canto; J Dingfelder; Z Doležal; TV Dong; M Dorigo; K Dugic; G Dujany; P Ecker; D Epifanov; J Eppelt; T Ferber; T Fillinger; C Finck; G Finocchiaro; A Fodor; F Forti; BG Fulsom; A Gabrielli; A Gale; M Garcia-Hernandez; L Gärtner; G Gaudino; V Gaur; A Gaz; A Gellrich; G Ghevondyan; D Ghosh

Journal article

Measurement of B → τ ντ branching fraction with a hadronic tagging method at Belle II

I Adachi, K Adamczyk, H Ahmed, Y Ahn, H Aihara, N Akopov, M Alhakami, A Aloisio, N Althubiti, M Angelsmark, NA Ky, DM Asner, H Atmacan, V Aushev, M Aversano, R Ayad, V Babu, NK Baghel, S Bahinipati, P Bambade Show all

Physical Review D | American Physical Society (APS) | Published : 2025

DOI: 10.1103/dcwd-5tg4

Abstract

We present a measurement of the branching fraction of B+ → τ+ντ decays using 387 ± 6 × 106 ϒ(4S) collected between 2019and2022 withtheBelle II detector at theSuperKEKBeþ e+ e- collider.We reconstruct the accompanying B- meson using the hadronic tagging method, while B+ → τ+ντ candidates are identified in the recoil. We find evidence for B+ → τ+ντ decays at 3.0 standard deviations, including systematic uncertainties.The measured branching fraction is(Formula presended.).