Search for lepton-flavor-violating τ– → μ–μ+μ– decays at Belle II

Adachi, I.; Aggarwal, L.; Aihara, H.; Akopov, N.; Aloisio, A.; Althubiti, N.; Anh Ky, N.; Asner, D. M.; Atmacan, H.; Aushev, V.; Aversano, M.; Ayad, R.; Babu, V.; Bae, H.; Bahinipati, S.; Bambade, P.; Banerjee, Sw; Bansal, S.; Barrett, M.; Baudot, J.; Baur, A.; Beaubien, A.; Becherer, F.; Becker, J.; Bennett, J. V.; Bernlochner, F. U.; Bertacchi, V.; Bertemes, M.; Bertholet, E.; Bessner, M.; Bettarini, S.; Bianchi, F.; Bierwirth, L.; Bilka, T.; Biswas, D.; Bobrov, A.; Bodrov, D.; Bolz, A.; Borah, J.; Boschetti, A.; Bozek, A.; Bračko, M.; Branchini, P.; Browder, T. E.; Budano, A.; Bussino, S.; Campagna, Q.; Campajola, M.; Cao, L.; Casarosa, G.; Cecchi, C.; Cerasoli, J.; Chang, M. -C.; Chang, P.; Cheaib, R.; Cheema, P.; Chen, C.; Cheon, B. G.; Chilikin, K.; Chirapatpimol, K.; Cho, H. -E.; Cho, K.; Cho, S. -J.; Choi, S. -K.; Choudhury, S.; Cochran, J.; Corona, L.; Cui, J. X.; Das, S.; Dattola, F.; De La Cruz-Burelo, E.; De La Motte, S. A.; De Nardo, G.; De Nuccio, M.; De Pietro, G.; de Sangro, R.; Destefanis, M.; Dey, S.; Dhamija, R.; Di Canto, A.; Di Capua, F.; Dingfelder, J.; Doležal, Z.; Domínguez Jiménez, I.; Dong, T. V.; Dorigo, M.; Dorner, D.; Dort, K.; Dossett, D.; Dreyer, S.; Dubey, S.; Dugic, K.; Dujany, G.; Ecker, P.; Eliachevitch, M.; Feichtinger, P.; Ferber, T.; Ferlewicz, D.; Fillinger, T.; Finck, C.; Finocchiaro, G.; Fodor, A.; Forti, F.; Frey, A.; Fulsom, B. G.; Gabrielli, A.; Ganiev, E.; Garcia-Hernandez, M.; Garg, R.; Gaudino, G.; Gaur, V.; Gaz, A.; Gellrich, A.; Ghevondyan, G.; Ghosh, D.; Ghumaryan, H.; Giakoustidis, G.; Giordano, R.; Giri, A.; Glazov, A.; Gobbo, B.; Godang, R.; Gogota, O.; Goldenzweig, P.; Gradl, W.; Grammatico, T.; Granderath, S.; Graziani, E.; Greenwald, D.; Gruberová, Z.; Gu, T.; Guan, Y.; Gudkova, K.; Halder, S.; Han, Y.; Hara, T.; Harris, C.; Hayasaka, K.; Hayashii, H.; Hazra, S.; Hearty, C.; Hedges, M. T.; Heidelbach, A.; Heredia de la Cruz, I.; Hernández Villanueva, M.; Higuchi, T.; Hoek, M.; Hohmann, M.; Horak, P.; Hsu, C. -L.; Humair, T.; Iijima, T.; Inami, K.; Inguglia, G.; Ipsita, N.; Ishikawa, A.; Itoh, R.; Iwasaki, M.; Jacobs, W. W.; Jaffe, D. E.; Jang, E. -J.; Ji, Q. P.; Jia, S.; Jin, Y.; Junkerkalefeld, H.; Kaleta, M.; Kalita, D.; Kaliyar, A. B.; Kandra, J.; Kang, K. H.; Kang, S.; Karyan, G.; Kawasaki, T.; Keil, F.; Kiesling, C.; Kim, C. -H.; Kim, D. Y.; Kim, K. -H.; Kim, Y. -K.; Kindo, H.; Kinoshita, K.; Kodyš, P.; Koga, T.; Kohani, S.; Kojima, K.; Konno, T.; Korobov, A.; Korpar, S.; Kovalenko, E.; Kowalewski, R.; Kraetzschmar, T. G.; Križan, P.; Krokovny, P.; Kuhr, T.; Kulii, Y.; Kumar, J.; Kumar, M.; Kumar, R.; Kumara, K.; Kunigo, T.; Kuzmin, A.; Kwon, Y. -J.; Lacaprara, S.; Lalwani, K.; Lam, T.; Lanceri, L.; Lange, J. S.; Laurenza, M.; Lautenbach, K.; Leboucher, R.; Le Diberder, F. R.; Lee, M. J.; Leo, P.; Lemettais, C.; Levit, D.; Lewis, P. M.; Li, L. K.; Li, S. X.; Li, Y.; Li, Y. B.; Libby, J.; Liu, M. H.; Liu, Q. Y.; Liu, Y.; Liu, Z. Q.; Liventsev, D.; Longo, S.; Lueck, T.; Lyu, C.; Ma, Y.; Maggiora, M.; Maharana, S. P.; Maiti, R.; Maity, S.; Mancinelli, G.; Manfredi, R.; Manoni, E.; Mantovano, M.; Marcantonio, D.; Marcello, S.; Marinas, C.; Martellini, C.; Martini, A.; Martinov, T.; Massaccesi, L.; Masuda, M.; Matsuoka, K.; Matvienko, D.; Maurya, S. K.; McKenna, J. A.; Mehta, R.; Meier, F.; Merola, M.; Metzner, F.; Miller, C.; Mirra, M.; Mitra, S.; Miyabayashi, K.; Mohanty, G. B.; Mondal, S.; Moneta, S.; Moser, H. -G.; Mrvar, M.; Mussa, R.; Nakamura, I.; Nakamura, K. R.; Nakao, M.; Nakazawa, Y.; Narimani Charan, A.; Naruki, M.; Narwal, D.; Natkaniec, Z.; Natochii, A.; Nayak, L.; Nayak, M.; Nazaryan, G.; Neu, M.; Niebuhr, C.; Ninkovic, J.; Nishida, S.; Ogawa, S.; Onishchuk, Y.; Ono, H.; Otani, F.; Pakhlov, P.; Pakhlova, G.; Pardi, S.; Parham, K.; Park, H.; Park, J.; Park, S. -H.; Paschen, B.; Passeri, A.; Patra, S.; Paul, S.; Pedlar, T. K.; Peschke, R.; Pestotnik, R.; Piccolo, M.; Piilonen, L. E.; Pinna Angioni, G.; Podesta-Lerma, P. M.; Podobnik, T.; Pokharel, S.; Praz, C.; Prell, S.; Prencipe, E.; Prim, M. T.; Prudiev, I.; Purwar, H.; Rados, P.; Raeuber, G.; Raiz, S.; Rauls, N.; Reif, M.; Reiter, S.; Reuter, L.; Ripp-Baudot, I.; Rizzo, G.; Robertson, S. H.; Roehrken, M.; Roney, J. M.; Rostomyan, A.; Rout, N.; Russo, G.; Sanders, D. A.; Sandilya, S.; Santelj, L.; Sato, Y.; Savinov, V.; Scavino, B.; Schneider, S.; Schwanda, C.; Schwickardi, M.; Seino, Y.; Selce, A.; Senyo, K.; Serrano, J.; Sevior, M. E.; Sfienti, C.; Shan, W.; Sharma, C.; Shen, C. P.; Shi, X. D.; Shillington, T.; Shimasaki, T.; Shiu, J. -G.; Shtol, D.; Sibidanov, A.; Simon, F.; Singh, J. B.; Skorupa, J.; Smith, K.; Sobie, R. J.; Sobotzik, M.; Soffer, A.; Sokolov, A.; Solovieva, E.; Spataro, S.; Spruck, B.; Starič, M.; Stavroulakis, P.; Stefkova, S.; Stroili, R.; Sue, Y.; Sumihama, M.; Sumisawa, K.; Sutcliffe, W.; Suwonjandee, N.; Svidras, H.; Takahashi, M.; Takizawa, M.; Tamponi, U.; Tanaka, S.; Tanida, K.; Tenchini, F.; Thaller, A.; Tittel, O.; Tiwary, R.; Tonelli, D.; Torassa, E.; Trabelsi, K.; Tsaklidis, I.; Ueda, I.; Uglov, T.; Unger, K.; Unno, Y.; Uno, K.; Uno, S.; Urquijo, P.; Ushiroda, Y.; Vahsen, S. E.; van Tonder, R.; Varvell, K. E.; Veronesi, M.; Vinokurova, A.; Vismaya, V. S.; Vitale, L.; Vobbilisetti, V.; Volpe, R.; Vossen, A.; Wach, B.; Wakai, M.; Wallner, S.; Wang, E.; Wang, M. -Z.; Wang, X. L.; Wang, Z.; Warburton, A.; Watanabe, M.; Watanuki, S.; Wessel, C.; Xu, X. P.; Yabsley, B. D.; Yamada, S.; Yan, W.; Yang, S. B.; Yelton, J.; Yin, J. H.; Yook, Y. M.; Yoshihara, K.; Yuan, C. Z.; Zani, L.; Zeng, F.; Zhang, B.; Zhang, Y.; Zhilich, V.; Zhou, Q. D.; Zhou, X. Y.; Zhukova, V. I.; Žlebčík, R.

doi:10.1007/jhep09(2024)062

Search for lepton-flavor-violating τ^– → μ^–μ⁺μ^– decays at Belle II

Journal Article · Wed Sep 11 00:00:00 EDT 2024 · Journal of High Energy Physics (Online)

DOI:https://doi.org/10.1007/jhep09(2024)062· OSTI ID:2446635

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We present the result of a search for the charged-lepton-flavor violating decay τ^– → μ^–μ⁺μ^– using a 424 fb^–1 sample of data recorded by the Belle II experiment at the SuperKEKB e⁺e^– collider. The selection of e⁺e^– → τ⁺τ^– events is based on an inclusive reconstruction of the non-signal tau decay, and on a boosted decision tree to suppress background. We observe one signal candidate, which is compatible with the expectation from background processes. We set a 90% confidence level upper limit of 1.9 × 10^–8 on the branching fraction of the τ^– → μ^–μ⁺μ^– decay, which is the most stringent bound to date.

View Accepted Manuscript (DOE)

Research Organization:: Brookhaven National Laboratory (BNL), Upton, NY (United States)

Sponsoring Organization:: USDOE Office of Science (SC), High Energy Physics (HEP)

Contributing Organization:: Belle II Collaboration

Grant/Contract Number:: SC0012704

OSTI ID:: 2446635

Report Number(s):: BNL--226133-2024-JAAM

Journal Information:: Journal of High Energy Physics (Online), Journal Name: Journal of High Energy Physics (Online) Journal Issue: 9 Vol. 2024; ISSN 1029-8479

Publisher:: Springer NatureCopyright Statement

Country of Publication:: United States

Language:: English

References (34)

Simultaneous explanation of the R K and R D * $$ {R}_{D^{\left(*\right)}} $$ puzzles: a model analysis Bhattacharya, Bhubanjyoti; Datta, Alakabha; Guévin, Jean-Pascal Journal of High Energy Physics, Vol. 2017, Issue 1 https://doi.org/10.1007/JHEP01(2017)015	journal	January 2017
On the breaking of lepton flavor universality in B decays Greljo, Admir; Isidori, Gino; Marzocca, David Journal of High Energy Physics, Vol. 2015, Issue 7 https://doi.org/10.1007/JHEP07(2015)142	journal	July 2015
On the importance of electroweak corrections for B anomalies Feruglio, Ferruccio; Paradisi, Paride; Pattori, Andrea Journal of High Energy Physics, Vol. 2017, Issue 9 https://doi.org/10.1007/JHEP09(2017)061	journal	September 2017
The Belle II Core Software: Belle II Framework Software Group Kuhr, T.; Pulvermacher, C.; Ritter, M. Computing and Software for Big Science, Vol. 3, Issue 1 https://doi.org/10.1007/s41781-018-0017-9	journal	November 2018
Monte Carlo simulation of two-photon processes Berends, F. A.; Daverveldt, P. H.; Kleiss, R. Computer Physics Communications, Vol. 40, Issue 2-3 https://doi.org/10.1016/0010-4655(86)90115-3	journal	June 1986
Photos — a universal Monte Carlo for QED radiative corrections in decays Barberio, Elisabetta; van Eijk, Bob; Wa̧s, Zbigniew Computer Physics Communications, Vol. 66, Issue 1 https://doi.org/10.1016/0010-4655(91)90012-A	journal	July 1991
TAUOLA - a library of Monte Carlo programs to simulate decays of polarized τ leptons Jadach, Stanisław; Kühn, Johann H.; Wa̧s, Zbigniew Computer Physics Communications, Vol. 64, Issue 2 https://doi.org/10.1016/0010-4655(91)90038-M	journal	May 1991
The principal axis of jets — an attempt to analyse high-energy collisions as two-body processes Brandt, S.; Peyrou, Ch.; Sosnowski, R. Physics Letters, Vol. 12, Issue 1 https://doi.org/10.1016/0031-9163(64)91176-X	journal	September 1964
Radiative corrections to the process e+e− → e+e−μ+μ− Berends, F. A.; Daverveldt, P. H.; Kleiss, R. Nuclear Physics B, Vol. 253 https://doi.org/10.1016/0550-3213(85)90540-1	journal	January 1985
Complete lowest-order calculations for four-lepton final states in electron-positron collisions Berends, F. A.; Daverveldt, P. H.; Kleiss, R. Nuclear Physics B, Vol. 253 https://doi.org/10.1016/0550-3213(85)90541-3	journal	January 1985
The precision Monte Carlo event generator for two-fermion final states in collisions Jadach, S.; Ward, B. F. L.; Wa̧s, Z. Computer Physics Communications, Vol. 130, Issue 3 https://doi.org/10.1016/S0010-4655(00)00048-5	journal	August 2000
The EvtGen particle decay simulation package Lange, David J. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 462, Issue 1-2 https://doi.org/10.1016/S0168-9002(01)00089-4	journal	April 2001
Geant4—a simulation toolkit Agostinelli, S.; Allison, J.; Amako, K. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 506, Issue 3 https://doi.org/10.1016/S0168-9002(03)01368-8	journal	July 2003
Confidence level computation for combining searches with small statistics Junk, Thomas Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 434, Issue 2-3 https://doi.org/10.1016/S0168-9002(99)00498-2	journal	September 1999
An improved parton shower algorithm in QED Carloni Calame, Carlo Michel Physics Letters B, Vol. 520, Issue 1-2 https://doi.org/10.1016/S0370-2693(01)01108-X	journal	November 2001
Large-angle Bhabha scattering and luminosity at flavour factories Carloni Calame, C. M.; Lunardini, C.; Montagna, G. Nuclear Physics B, Vol. 584, Issue 1-2 https://doi.org/10.1016/S0550-3213(00)00356-4	journal	September 2000
BAT – The Bayesian analysis toolkit Caldwell, Allen; Kollár, Daniel; Kröninger, Kevin Computer Physics Communications, Vol. 180, Issue 11 https://doi.org/10.1016/j.cpc.2009.06.026	journal	November 2009
An introduction to PYTHIA 8.2 Sjöstrand, Torbjörn; Ask, Stefan; Christiansen, Jesper R. Computer Physics Communications, Vol. 191 https://doi.org/10.1016/j.cpc.2015.01.024	journal	June 2015
SuperKEKB collider Akai, Kazunori; Furukawa, Kazuro; Koiso, Haruyo Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 907 https://doi.org/10.1016/j.nima.2018.08.017	journal	November 2018
Matching perturbative and parton shower corrections to Bhabha process at flavour factories Balossini, Giovanni; Carloni Calame, Carlo M.; Montagna, Guido Nuclear Physics B, Vol. 758, Issue 1-2 https://doi.org/10.1016/j.nuclphysb.2006.09.022	journal	December 2006
The BABAYAGA event generator Carloni Calame, C. M.; Montagna, G.; Nicrosini, O. Nuclear Physics B - Proceedings Supplements, Vol. 131 https://doi.org/10.1016/j.nuclphysbps.2004.02.008	journal	April 2004
Photon pair production at flavour factories with per mille accuracy Balossini, G.; Bignamini, C.; Carloni Calame, C. M. Physics Letters B, Vol. 663, Issue 3 https://doi.org/10.1016/j.physletb.2008.04.007	journal	May 2008
Search for lepton-flavor-violating τ decays into three leptons with 719 million produced τ+τ− pairs Hayasaka, K.; Inami, K.; Miyazaki, Y. Physics Letters B, Vol. 687, Issue 2-3 https://doi.org/10.1016/j.physletb.2010.03.037	journal	April 2010
Presentation of search results: the CL _s technique Read, A. L. Journal of Physics G: Nuclear and Particle Physics, Vol. 28, Issue 10 https://doi.org/10.1088/0954-3899/28/10/313	journal	September 2002
Theoretical aspects of charged Lepton Flavour Violation Teixeira, Ana M. Journal of Physics: Conference Series, Vol. 888 https://doi.org/10.1088/1742-6596/888/1/012029	journal	September 2017
Tau and muon pair production cross sections in electron-positron annihilations at s = 10.58 GeV Banerjee, Swagato; Pietrzyk, Bolek; Roney, J. Michael Physical Review D, Vol. 77, Issue 5 https://doi.org/10.1103/PhysRevD.77.054012	journal	March 2008
Quantum Chromodynamics Test for Jets Farhi, Edward Physical Review Letters, Vol. 39, Issue 25 https://doi.org/10.1103/PhysRevLett.39.1587	journal	December 1977
Flavor physics of leptons and dipole moments Raidal, M.; van der Schaaf, A.; Bigi, I. The European Physical Journal C, Vol. 57, Issue 1-2 https://doi.org/10.1140/epjc/s10052-008-0715-2	journal	September 2008
Flavor violating leptonic decays of $$\tau $$ τ and $$\mu $$ μ leptons in the Standard Model with massive neutrinos Hernández-Tomé, G.; López Castro, G.; Roig, P. The European Physical Journal C, Vol. 79, Issue 1 https://doi.org/10.1140/epjc/s10052-019-6563-4	journal	January 2019
$$\tau \rightarrow \mu \mu \mu $$ at a rate of one out of $$10^{14}$$ tau decays? Blackstone, Patrick; Fael, Matteo; Passemar, Emilie The European Physical Journal C, Vol. 80, Issue 6 https://doi.org/10.1140/epjc/s10052-020-8059-7	journal	June 2020
Charged lepton flavor violation in light of the muon magnetic moment anomaly and colliders Li, Tong; Schmidt, Michael A.; Yao, Chang-Yuan The European Physical Journal C, Vol. 81, Issue 9 https://doi.org/10.1140/epjc/s10052-021-09569-9	journal	September 2021
On the role of leptonic CPV phases in cLFV observables Abada, A.; Kriewald, J.; Teixeira, A. M. The European Physical Journal C, Vol. 81, Issue 11 https://doi.org/10.1140/epjc/s10052-021-09754-w	journal	November 2021
XGBoost: A Scalable Tree Boosting System Chen, Tianqi; Guestrin, Carlos Proceedings of the 22nd ACM SIGKDD International Conference on Knowledge Discovery and Data Mining - KDD '16 https://doi.org/10.1145/2939672.2939785	conference	January 2016
Beating the hold-out: bounds for K-fold and progressive cross-validation Blum, Avrim; Kalai, Adam; Langford, John Proceedings of the twelfth annual conference on Computational learning theory - COLT '99 https://doi.org/10.1145/307400.307439	conference	January 1999

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