First Search for B →Xsν ν ¯ Decays

M Abumusabh; I Adachi; K Adamczyk; L Aggarwal; H Ahmed; Y Ahn; H Aihara; N Akopov; S Alghamdi; M Alhakami; A Aloisio; N Althubiti; K Amos; 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; V Bhardwaj; B Bhuyan; F Bianchi; T Bilka; D Biswas; A Bobrov; D Bodrov; A Bondar; G Bonvicini; 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 Chang; P Cheema; L Chen; BG Cheon; C Cheshta; H Chetri; K Chilikin; J Chin; K Chirapatpimol; HE Cho; K Cho; SJ Cho; SK Choi; S Choudhury; JA Colorado-Caicedo; I Consigny; 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; A Di Canto; J Dingfelder; Z DoleŽal; I Domínguez Jiménez; TV Dong; X Dong; K Dugic; G Dujany; P Ecker; R Farkas

Journal article

First Search for B →Xsν ν ¯ Decays

M Abumusabh, I Adachi, K Adamczyk, L Aggarwal, H Ahmed, Y Ahn, H Aihara, N Akopov, S Alghamdi, M Alhakami, A Aloisio, N Althubiti, K Amos, N Anh Ky, C Antonioli, DM Asner, H Atmacan, T Aushev, M Aversano, R Ayad Show all

Physical Review Letters | American Physical Society (APS) | Published : 2026

DOI: 10.1103/kf73-hw61

Open access

Abstract

We report the first search for the flavor-changing neutral-current decays B→Xsνν¯, where Xs is a hadronic system with strangeness equal to 1, in data collected with the Belle II detector at the SuperKEKB asymmetric-energy e+e- collider. The data sample corresponds to an integrated luminosity of 365 fb-1 collected at the δ(4S) resonance and 43 fb-1 collected at a center-of-mass energy 60 MeV below resonance for estimation of e+e-→qq¯ continuum background. One of the B mesons from the δ(4S)→BB¯ decay is fully reconstructed in a hadronic decay mode. The B→Xsνν¯ decay is reconstructed with a sum-of-exclusives approach that uses 30 Xs decay modes. This approach provides high sensitivity to the in..

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