A new graph-neural-network flavor tagger for Belle II and measurement of
sin2ϕ_1 in B^0 → J/ψ K^0_S decays
Belle II Collaboration,I. Adachi,L. Aggarwal,H. Ahmed,H. Aihara,N. Akopov,A. Aloisio,N. Anh Ky,D. M. Asner,H. Atmacan,T. Aushev,V. Aushev,M. Aversano,R. Ayad,V. Babu,H. Bae,S. Bahinipati,P. Bambade,Sw. Banerjee,S. Bansal,M. Barrett,J. Baudot,A. Baur,A. Beaubien,F. Becherer,J. Becker,J. V. Bennett,F. U. Bernlochner,V. Bertacchi,M. Bertemes,E. Bertholet,M. Bessner,S. Bettarini,B. Bhuyan,F. Bianchi,L. Bierwirth,T. Bilka,S. Bilokin,D. Biswas,A. Bobrov,D. Bodrov,A. Bolz,A. Bondar,A. Bozek,M. Bračko,P. Branchini,R. A. Briere,T. E. Browder,A. Budano,S. Bussino,M. Campajola,L. Cao,G. Casarosa,C. Cecchi,J. Cerasoli,M. -C. Chang,P. Chang,P. Cheema,C. Chen,B. G. Cheon,K. Chilikin,K. Chirapatpimol,H. -E. Cho,K. Cho,S. -J. Cho,S. -K. Choi,S. Choudhury,J. Cochran,L. Corona,S. Das,F. Dattola,E. De La Cruz-Burelo,S. A. De La Motte,G. De Nardo,M. De Nuccio,G. De Pietro,R. de Sangro,M. Destefanis,S. Dey,R. Dhamija,A. Di Canto,F. Di Capua,Z. Doležal,T. V. Dong,M. Dorigo,K. Dort,D. Dossett,S. Dreyer,S. Dubey,G. Dujany,P. Ecker,M. Eliachevitch,P. Feichtinger,T. Ferber,D. Ferlewicz,T. Fillinger,C. Finck,G. Finocchiaro,A. Fodor,F. Forti,A. Frey,B. G. Fulsom,A. Gabrielli,E. Ganiev,M. Garcia-Hernandez,R. Garg,G. Gaudino,V. Gaur,A. Gaz,A. Gellrich,G. Ghevondyan,D. Ghosh,H. Ghumaryan,G. Giakoustidis,R. Giordano,A. Giri,A. Glazov,B. Gobbo,R. Godang,O. Gogota,P. Goldenzweig,W. Gradl,T. Grammatico,E. Graziani,D. Greenwald,Z. Gruberová,T. Gu,Y. Guan,K. Gudkova,Y. Han,K. Hara,T. Hara,K. Hayasaka,H. Hayashii,S. Hazra,C. Hearty,M. T. Hedges,A. Heidelbach,I. Heredia de la Cruz,M. Hernández Villanueva,T. Higuchi,M. Hoek,M. Hohmann,P. Horak,C. -L. Hsu,T. Humair,T. Iijima,K. Inami,N. Ipsita,A. Ishikawa,R. Itoh,M. Iwasaki,P. Jackson,W. W. Jacobs,D. E. Jaffe,E. -J. Jang,Q. P. Ji,S. Jia,Y. Jin,K. K. Joo,H. Junkerkalefeld,H. Kakuno,D. Kalita,A. B. Kaliyar,J. Kandra,K. H. Kang,S. Kang,G. Karyan,T. Kawasaki,F. Keil,C. Kiesling,C. -H. Kim,D. Y. Kim,K. -H. Kim,Y. -K. Kim,H. Kindo,K. Kinoshita,P. Kodyš,T. Koga,S. Kohani,K. Kojima,A. Korobov,S. Korpar,E. Kovalenko,R. Kowalewski,T. M. G. Kraetzschmar,P. Križan,P. Krokovny,T. Kuhr,Y. Kulii,J. Kumar,M. Kumar,R. Kumar,K. Kumara,T. Kunigo,A. Kuzmin,Y. -J. Kwon,S. Lacaprara,Y. -T. Lai,T. Lam,L. Lanceri,J. S. Lange,M. Laurenza,R. Leboucher,F. R. Le Diberder,M. J. Lee,D. Levit,C. Li,L. K. Li,Y. Li,Y. B. Li,J. Libby,Y. -R. Lin,M. H. Liu,Q. Y. Liu,Z. Q. Liu,D. Liventsev,S. Longo,T. Lueck,C. Lyu,Y. Ma,M. Maggiora,S. P. Maharana,R. Maiti,S. Maity,G. Mancinelli,R. Manfredi,E. Manoni,M. Mantovano,D. Marcantonio,S. Marcello,C. Marinas,L. Martel,C. Martellini,A. Martini,T. Martinov,L. Massaccesi,M. Masuda,K. Matsuoka,D. Matvienko,S. K. Maurya,J. A. McKenna,R. Mehta,F. Meier,M. Merola,F. Metzner,C. Miller,M. Mirra,S. Mitra,K. Miyabayashi,H. Miyake,R. Mizuk,G. B. Mohanty,N. Molina-Gonzalez,S. Mondal,S. Moneta,H. -G. Moser,M. Mrvar,R. Mussa,I. Nakamura,K. R. Nakamura,M. Nakao,Y. Nakazawa,A. Narimani Charan,M. Naruki,D. Narwal,Z. Natkaniec,A. Natochii,L. Nayak,M. Nayak,G. Nazaryan,M. Neu,C. Niebuhr,S. Nishida,S. Ogawa,Y. Onishchuk,H. Ono,Y. Onuki,P. Oskin,F. Otani,P. Pakhlov,G. Pakhlova,A. Panta,S. Pardi,K. Parham,H. Park,S. -H. Park,B. Paschen,A. Passeri,S. Patra,S. Paul,T. K. Pedlar,R. Peschke,R. Pestotnik,M. Piccolo,L. E. Piilonen,G. Pinna Angioni,P. L. M. Podesta-Lerma,T. Podobnik,S. Pokharel,C. Praz,S. Prell,E. Prencipe,M. T. Prim,H. Purwar,P. Rados,G. Raeuber,S. Raiz,N. Rauls,M. Reif,S. Reiter,M. Remnev,I. Ripp-Baudot,G. Rizzo,M. Roehrken,J. M. Roney,A. Rostomyan,N. Rout,G. Russo,D. A. Sanders,S. Sandilya,A. Sangal,L. Santelj,Y. Sato,V. Savinov,B. Scavino,C. Schmitt,C. Schwanda,M. Schwickardi,Y. Seino,A. Selce,K. Senyo,J. Serrano,M. E. Sevior,C. Sfienti,W. Shan,X. D. Shi,T. Shillington,T. Shimasaki,J. -G. Shiu,D. Shtol,A. Sibidanov,F. Simon,J. B. Singh,J. Skorupa,R. J. Sobie,M. Sobotzik,A. Soffer,A. Sokolov,E. Solovieva,S. Spataro,B. Spruck,M. Starič,P. Stavroulakis,S. Stefkova,R. Stroili,M. Sumihama,K. Sumisawa,W. Sutcliffe,H. Svidras,M. Takizawa,U. Tamponi,S. Tanaka,K. Tanida,F. Tenchini,O. Tittel,R. Tiwary,D. Tonelli,E. Torassa,K. Trabelsi,I. Tsaklidis,M. Uchida,I. Ueda,Y. Uematsu,K. Unger,Y. Unno,K. Uno,S. Uno,P. Urquijo,Y. Ushiroda,S. E. Vahsen,R. van Tonder,K. E. Varvell,M. Veronesi,A. Vinokurova,V. S. Vismaya,L. Vitale,V. Vobbilisetti,R. Volpe,B. Wach,M. Wakai,S. Wallner,E. Wang,M. -Z. Wang,X. L. Wang,Z. Wang,A. Warburton,S. Watanuki,C. Wessel,E. Won,X. P. Xu,B. D. Yabsley,S. Yamada,W. Yan,S. B. Yang,J. Yelton,J. H. Yin,K. Yoshihara,C. Z. Yuan,Y. Yusa,B. Zhang,V. Zhilich,Q. D. Zhou,X. Y. Zhou,V. I. Zhukova,R. Žlebčík
arxiv（2024）
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摘要
We present GFlaT, a new algorithm that uses a graph-neural-network to
determine the flavor of neutral B mesons produced in Υ(4S) decays.
It improves previous algorithms by using the information from all charged
final-state particles and the relations between them. We evaluate its
performance using B decays to flavor-specific hadronic final states
reconstructed in a 362 fb^-1 sample of electron-positron collisions
collected at the Υ(4S) resonance with the Belle II detector at the
SuperKEKB collider. We achieve an effective tagging efficiency of (37.40 ±
0.43 ± 0.36) %, where the first uncertainty is statistical and the second
systematic, which is 18% better than the previous Belle II algorithm.
Demonstrating the algorithm, we use B^0→ J/ψ K^0_S decays to
measure the mixing-induced and direct CP violation parameters, S = (0.724
± 0.035 ± 0.014) and C = (-0.035 ± 0.026 ± 0.013).
