Measurement of the branching fraction and CP -violating asymmetry of the decay B0 →π0π0 using 387 million ϒ (4S) decays in Belle II data

I Adachi; L Aggarwal; H Ahmed; H Aihara; M Alhakami; 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; M Barrett; M Bartl; 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; B Bhuyan; F Bianchi; T Bilka; D Biswas; A Bobrov; D Bodrov; A Bolz; 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; 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 Marino; G De Nardo; G De Pietro; R De Sangro; M Destefanis; S Dey; R Dhamija; A Di Canto; F Di Capua; J Dingfelder; Z DoleŽal; I Domínguez Jiménez; TV Dong; X Dong; M Dorigo; D Dossett; S Dubey; K Dugic; G Dujany; P Ecker; D Epifanov; J Eppelt; P Feichtinger; T Ferber; T Fillinger

Journal article

Measurement of the branching fraction and CP -violating asymmetry of the decay B0 →π0π0 using 387 million ϒ (4S) decays in Belle II data

I Adachi, L Aggarwal, H Ahmed, H Aihara, M Alhakami, 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.L071102

Abstract

We measure the branching fraction and CP-violating flavor-dependent rate asymmetry of B0→π0π0 decays reconstructed using the Belle II detector in an electron-positron collision sample containing 387×106 ϒ(4S) mesons. Using an optimized event selection, we find 125±20 signal decays in a fit to background-discriminating and flavor-sensitive distributions. The resulting branching fraction is (1.25±0.23)×10-6 and the CP-violating asymmetry is 0.03±0.30.