Measurement of the time-integrated CP asymmetry in D0 → π0π0 decays at Belle II

I Adachi; Y Ahn; N Akopov; S Alghamdi; M Alhakami; A Aloisio; N Althubiti; K Amos; M Angelsmark; N Anh Ky; C Antonioli; DM Asner; H Atmacan; T Aushev; M Aversano; R Ayad; V Babu; H Bae; NK Baghel; S Bahinipati; P Bambade; S Banerjee; 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; B Bhuyan; 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; M Campajola; L Cao; G Casarosa; C Cecchi; P Cheema; BG Cheon; K Chilikin; J Chin; K Chirapatpimol; 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 Pietro; R de Sangro; M Destefanis; A Di Canto; J Dingfelder; Z Doležal; I Domínguez Jiménez; TV Dong; M Dorigo; G Dujany; P Ecker; D Epifanov; J Eppelt; R Farkas; P Feichtinger; T Ferber; T Fillinger; C Finck; G Finocchiaro; A Fodor; F Forti; BG Fulsom; A Gabrielli; A Gale; E Ganiev; M Garcia-Hernandez; R Garg; G Gaudino; V Gaur

Journal article

Measurement of the time-integrated CP asymmetry in D0 → π0π0 decays at Belle II

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

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

DOI: 10.1103/vg9c-xvdc

Abstract

We measure the time-integrated CP asymmetry, ACP, in D0 → π0π0 decays reconstructed in e+e− → cc̄ events collected by Belle II during 2019–2022. The data corresponds to an integrated luminosity of 428 fb−1. The D0 decays are required to originate from the flavor-conserving D*+ → D0π+ decay to determine the charm flavor at production time. Control samples of D0 → K−π+ decays, with or without an associated pion from a D*+ decay, are used to correct for detection asymmetries. The result, ACP(D0 → π0π0) = (0.30 ± 0.72 ± 0.20)%, where the first uncertainty is statistical and the second systematic, is consistent with CP symmetry.