Observation of time-dependent CP violation and measurement of the branching fraction of B0 →j/ψπ0 decays

I Adachi; L Aggarwal; H Ahmed; H Aihara; N Akopov; A Aloisio; N Althubiti; N Anh Ky; DM Asner; H Atmacan; V Aushev; M Aversano; R Ayad; V Babu; H Bae; NK Baghel; S Bahinipati; P Bambade; S Banerjee; S Bansal; J Baudot; A Baur; A Beaubien; F Becherer; J Becker; JV Bennett; FU Bernlochner; V Bertacchi; M Bertemes; E Bertholet; M Bessner; S Bettarini; V Bhardwaj; F Bianchi; T Bilka; 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; J Cerasoli; MC Chang; P Chang; R Cheaib; P Cheema; C Chen; 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; R Dhamija; A Di Canto; F Di Capua; J Dingfelder; Z DoleŽal; TV Dong; M Dorigo; S Dubey; K Dugic; G Dujany; P Ecker; D Epifanov; P Feichtinger; T Ferber; T Fillinger; C Finck; G Finocchiaro; A Fodor; F Forti; BG Fulsom; A Gabrielli; E Ganiev; M Garcia-Hernandez; R Garg

Journal article

Observation of time-dependent CP violation and measurement of the branching fraction of B0 →j/ψπ0 decays

I Adachi, L Aggarwal, H Ahmed, H Aihara, N Akopov, A Aloisio, N Althubiti, N Anh Ky, DM Asner, H Atmacan, V Aushev, M Aversano, R Ayad, V Babu, H Bae, NK Baghel, S Bahinipati, P Bambade, S Banerjee, S Bansal Show all

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

DOI: 10.1103/PhysRevD.111.012011

Abstract

We present a measurement of the branching fraction and time-dependent charge-parity (CP) decay-rate asymmetries in B0→J/ψπ0 decays. The data sample was collected with the Belle II detector at the SuperKEKB asymmetric e+e- collider in 2019-2022 and contains (387±6)×106 BB¯ meson pairs from ϒ(4S) decays. We reconstruct 392±24 signal decays and fit the CP parameters from the distribution of the proper-decay-time difference of the two B mesons. We measure the branching fraction to be (B0→J/ψπ0)=(2.00±0.12±0.09)×10-5 and the direct and mixing-induced CP asymmetries to be CCP=0.13±0.12±0.03 and SCP=-0.88±0.17±0.03, respectively, where the first uncertainties are statistical and the second are syst..

View full abstract