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Measurement of the branching fraction and $\it CP$-violating asymmetry of the decay $B^{0} \rightarrow \pi^{0} \pi^{0}$ using $387$ million bottom-antibottom meson pairs in Belle II data
Ichiro Adachi, L. Aggarwal, H. Ahmed, H. Aihara, M. Alhakami, A. Aloisio, N. Althubiti, Anh-Ky Nguyen, D. M. Asner, H. Atmacan, V. Aushev, M. Aversano, R. Ayad, Varghese Babu, S. Bahinipati, P. Bambade, S. Banerjee, S. Bansal, J. Baudot, A. Baur, A. Beaubien, F. Becherer, J. V. Bennett, E. Bertholet, M. Bessner, Bipul Bhuyan, F. Bianchi, T. Bilka, D. Biswas, A. Bobrov, D. Bodrov, A. E. Bolz, J. Borah, A. Boschetti, A. Bożek, Marko Bračko, P. Branchini, M. Campajola, Ming-Chuan Chang, P. Chang, P. Cheema, B. G. Cheon, K. Chirapatpimol, Haneol Cho, K. Cho, S. K. Choi, L. Corona, J. X. Cui, E. De La Cruz–Burelo, Guglielmo De Nardo, G. De Pietro, A. Di Canto, J. Dingfelder, Z. Doležal, I. Domínguez Jiménez, T. V. Dong, M. Dorigo, D. Dossett, K. Dugic, G. Dujany, P. Ecker, P. Feichtinger, T. Ferber, C. Finck, G. Finocchiaro, B. G. Fulsom, E. Ganiev, Marcela Garcia Hernandez, G. Gaudino, V. Gaur, A. Gaz, D. Ghosh, G. Giakoustidis, R. Giordano, A. Giri, B. Gobbo, Wolfgang Gradl, Svenja Katharina Granderath, E. Graziani, Yinghui Guan, I. Haide, Y. Han, Takanori Hara, C. Harris, K. Hayasaka, Sagar Hazra, C. Hearty, Michael Thomas Hedges, A. Heidelbach, I. Heredia-De La Cruz, M. Hernández Villanueva, M. Hoek, Philipp Horak, Toru Iijima, A. Ishikawa, M. Iwasaki, William Wescott Jacobs, Eunji Jang, Q. P. Ji, Y. Jin, A. Johnson, K. K. Joo, H. Junkerkalefeld, Dibyajyoti Kalita, A. B. Kaliyar, K. H. Kang, G. Karyan, T. Kawasaki, Felix Keil, C. Ketter, C. Kiesling, Doris Yangsoo Kim, Kyungho Kim, Yong Kyun Kim, K. Kinoshita, T. Koga, S. Kohani, K. Kojima, Samo Korpar, E. Kovalenko, T. Kuhr, Devender Kumar, Rajeev Kumar, Y.-J. Kwon, S. Lacaprara, Y.-T. Lai, K. Lalwani, Tommy Lam, L. Lanceri, J. S. Lange, T. S. Lau, M. Laurenza, K. Lautenbach, R. Leboucher, Francois Rene Le Diberder, Paolo Leo, D. Levit, P. Lewis, L. K. Li, Wenzhe Li, Yubo Li, Yipu Liao, J. Libby, Shu-Ping Lin, Meihong Liu, Qingyuan Liu, Zhiqing Liu, D. Liventsev, C. Madaan, M. Maggiora, S. P. Maharana, G. Mancinelli, R. Manfredi, D. Marcantonio, S. Marcello, A. Martens, Tommy Martinov, L. Massaccesi, Masataka Masuda, T. Matsuda, M. Maushart, J. A. McKenna, D. Meleshko, M. Merola, C. Miller, M. Mirra, S. Mitra, K. Miyabayashi, R. Mizuk, G. B. Mohanty, S. Moneta, R. Mussa, I. Nakamura, Mikihiko Nakao, Y. Nakazawa, M. Naruki, A. Natochii, M. Nayak, M. Neu, C. Niebuhr, Hiroaki Ono, Y. Onuki, F. Otani, P. Pakhlov, G. Pakhlova, E. Paoloni, H. Park, J. Park, K. Park, S.-H. Park, B. Paschen, A. Passeri, S. Patra, T. K. Pedlar, R. Pestotnik, M. Piccolo, Pedro Luis Manuel Podesta Lerma, T. Podobnik, C. Praz, S. Prell, P. Rados, G. Raeuber, S. Raiz, Vikas Gotti Rajg, J. U. Rehman, M. Reif, S. Reiter, L. Reuter, D. Ricalde Herrmann, I. Ripp-Baudot, G. Rizzo, M. Röhrken, J. M. Roney, A. Rostomyan, L. Šantelj, Y. Sato, V. Savinov, B. Scavino, C. Schmitt, Simon Schneider, M. Schnepf, C. Schwanda, A. J. Schwartz, Yoshiaki Seino, K. Senyo, J. Serrano, W. Shan, Chanchal Sharma, T. Shillington, T. Shimasaki, D. Shtol, R. Sobie, A. Sokolov, E. Solovieva, W. Y. Song, M. Starič, P. Stavroulakis, R. Stroili, M. Sumihama, K. Sumisawa, W. Sutcliffe, N. Suwonjandee, H. Svidras, A. Thaller, O. Tittel, R. Tiwary, D. Tonelli, M. Uchida, I. Ueda, Y. Unno, S. Uno, Sven Einar Vahsen, K. E. Varvell, M. Veronesi, L. Vitale, Vidya Sagar Vobbilisetti, R. Volpe, A. Vossen, S. Wallner, Zihan Wang, A. Warburton, Minori Watanabe, Shun Watanuki, Xinping Xu, S. Yamada, J. Yelton, Keisuke Yoshihara, Boyang Zhang, V. Zhilich, Jianshe Zhou, V. Zhukova, R. Žlebčík
Bibliographic record
VenuearXiv (Cornell University) · 2024
Typepreprint
Languageen
FieldPhysics and Astronomy
TopicParticle physics theoretical and experimental studies
Canadian institutionsnot available
FundersInstitut National de Physique Nucléaire et de Physique des ParticulesAkademi Sains MalaysiaJapan Society for the Promotion of ScienceNatural Sciences and Engineering Research Council of CanadaKorea Research Environment Open NetworkNational Science and Technology CouncilCentro de Investigación y de Estudios Avanzados del Instituto Politécnico NacionalIstituto Nazionale di Fisica NucleareNational Research University Higher School of EconomicsJavna Agencija za Raziskovalno Dejavnost RSKnut och Alice Wallenbergs StiftelseNational Research FoundationAustrian Science FundDeutsches Elektronen-SynchrotronThailand Center of Excellence in PhysicsGeneralitat ValencianaKing Saud UniversityU.S. Department of EnergyNational Natural Science Foundation of ChinaKorea Institute of Science and Technology InformationMinistry of Education, Culture, Sports, Science and TechnologyDeutsche ForschungsgemeinschaftMax-Planck-GesellschaftNational Research Foundation of UkraineGrantová Agentura České RepublikyAlexander von Humboldt-StiftungBundesministerium für Bildung, Wissenschaft und ForschungMinistry of Education and Science of UkraineVietnam Academy of Science and TechnologyNatural Science Foundation of Shandong ProvinceCompute CanadaUniversity of TabukNational Science FoundationKorea Institute of Science and TechnologyBundesministerium für Bildung und ForschungCanarieTürkiye Bilimsel ve Teknolojik Araştırma KurumuAgence Nationale de la RechercheGrantová Agentura, Univerzita KarlovaCentre National de la Recherche ScientifiqueUniverzita Karlova v PrazeEuropean Commission
KeywordsAsymmetryPhysicsBranching fractionPiParticle physicsB mesonBranching (polymer chemistry)Nuclear physicsMesonElectron–positron annihilationChemistryHadronMathematicsGeometry
Abstract
We measure the branching fraction and $\it CP$-violating flavor-dependent rate asymmetry of $B^{0} \to \pi^{0} \pi^{0}$ decays reconstructed using the Belle II detector in an electron-positron collision sample containing $387 \times 10^{6}$$B\overline{B}$ pairs. Using an optimized event selection, we find $126\pm 20$ signal decays in a fit to background-discriminating and flavor-sensitive distributions. The resulting branching fraction is $(1.25 \pm 0.23)\times 10^{-6}$ and the $\it CP$-violating asymmetry is $0.03 \pm 0.30$.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
metaresearch head score (Codex)0.002
metaresearch head score (Gemma)0.002
Version: metacan-v3-hybrid-931329e0061cValidation status: machine_predicted_unvalidated
Candidate categoriesnone
Consensus categoriesnone
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Bench or experimental · Consensus signal: none
GenreCandidate signal: Empirical · Consensus signal: Empirical
Teacher disagreement score0.003
Threshold uncertainty score0.010
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
Opus teacher head0.076
GPT teacher head0.232
Teacher spread0.156 · how far apart the two teachers sit on this one work
Validation status
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
The models applied no category: nothing in the taxonomy fit this work.
Study designBench or experimental
Domainnot available
GenreEmpirical
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".
Quick stats
Citations0
Published2024
Admission routes1
Has abstractyes