Test of light-lepton universality in $\tau$ decays with the Belle II experiment
Creators: name: Adachi, Ichiro
name: Adamczyk, Karol Mateusz
name: Aggarwal, Latika
name: Aihara, Hiroaki
name: Akopov, Norayr
name: Aloisio, Alberto
name: Nguyen, Anh-Ky
name: Asner, David Mark
name: Atmacan, Hulya
name: Aushev, Volodymyr Ye
name: Aversano, Michele
name: Ayad, Rachid
name: Babu, Varghese
name: Bae, Hanwook
name: Bahinipati, Seema
name: Bambade, Philip
name: Banerjee, Swagato
name: Bansal, Sunil
name: Barrett, Matthew
name: Baudot, Jerome
name: Baur, Anselm
name: Beaubien, Alexandre
name: Becherer, Fabian Horst
name: Becker, Juergen
name: Bennett, Jake
name: Bernlochner, Florian
name: Bertacchi, Valerio
name: Bertemes, Michel
name: Bertholet, Emilie
name: Bessner, Martin
name: Bettarini, Stefano
name: Bianchi, Fabrizio
name: Bierwirth, Lukas
name: Bilka, Tadeas
name: Bilokin, Sviatoslav
name: Biswas, Diptaparna
name: Bobrov, Alexander
name: Bodrov, Denis
name: Bolz, Arthur
name: Borah, Jyotirmoi
name: Boschetti, Alessandro
name: Bozek, Andrzej
name: Bracko, Marko
name: Branchini, Paolo
name: Browder, Thomas Earl
name: Budano, Antonio
name: Bussino, Severino
name: Campajola, Marcello
name: Cao, Lu
name: Casarosa, Giulia
name: Cecchi, Claudia
name: Cerasoli, Jacopo
name: Chang, Ming-Chuan
name: Chang, Paoti
name: Cheaib, Racha
name: Cheema, Priyanka
name: Cheon, ByungGu
name: Chilikin, Kirill
name: Chirapatpimol, Khem
name: Cho, HanEol
name: Cho, Kihyeon
name: Cho, Sungjin
name: Choi, Sookyung
name: Choudhury, Seema
name: Corona, Luigi
name: Cui, Junxi
name: Das, Sanjeeda Bharati
name: Dattola, Filippo
name: De La Cruz Burelo, Eduard
name: De La Motte, Shanette Anne
name: de Marino, Gaetano
name: De Nardo, Guglielmo
name: De Nuccio, Michael
name: De Pietro, Giacomo
name: de Sangro, Riccardo
name: Destefanis, Marco
name: Dey, Sourav
name: Dhamija, Rashmi
name: Di Canto, Angelo
name: Di Capua, Francesco
name: Dingfelder, Jochen
name: Dolezal, Zdenek
name: Dominguez Jimenez, Isabel
name: Dong, Thanh Van
name: Dorigo, Mirco
name: Dorner, Daniel
name: Dort, Katharina
name: Dossett, David
name: Dreyer, Sascha
name: Dubey, Shawn
name: Dugic, Katarina
name: Dujany, Giulio
name: Ecker, Patrick
name: Eliachevitch, Michael
name: Epifanov, Denis Alexandrovich
name: Feichtinger, Paul
name: Ferber, Torben
name: Ferlewicz, Daniel
name: Fillinger, Tristan
name: Finck, Christian
name: Finocchiaro, Giuseppe
name: Fodor, Andrea
name: Forti, Francesco
name: Frey, Ariane
name: Fulsom, Bryan Gregory
name: Gabrielli, Alice
name: Ganiev, Eldar
name: Garcia Hernandez, Marcela
name: Gaudino, Giovanni
name: Gaur, Vipin
name: Gaz, Alessandro
name: Gellrich, Andreas
name: Ghevondyan, Gayane
name: Ghosh, Debjit
name: Ghumaryan, Hazaravard
name: Giakoustidis, Georgios
name: Giordano, Raffaele
name: Giri, Anjan
name: Glazov, Alexander
name: Gobbo, Benigno
name: Godang, Romulus
name: Gogota, Olga
name: Goldenzweig, Pablo
name: Gradl, Wolfgang
name: Grammatico, Thomas
name: Granderath, Svenja Katharina
name: Graziani, Enrico
name: Greenwald, Daniel
name: Gruberova, Zuzana
name: Gu, Tianping
name: Guan, Yinghui
name: Gudkova, Kristina
name: Han, Yubo
name: Hara, Takanori
name: Hayasaka, Kiyoshi
name: Hayashii, Hisaki
name: Hazra, Sagar
name: Hearty, Christopher
name: Hedges, Michael Thomas
name: Heidelbach, Alexander
name: Heredia de la Cruz, Ivan
name: Hernandez Villanueva, Michel
name: Higuchi, Takeo
name: Hoek, Matthias
name: Hohmann, Marcel
name: Horak, Philipp
name: Hsu, Chia-Ling
name: Humair, Thibaud
name: Iijima, Toru
name: Inami, Kenji
name: Inguglia, Gianluca
name: Ipsita, N. Sushree
name: Ishikawa, Akimasa
name: Itoh, Ryosuke
name: Iwasaki, Masako
name: Jacobs, William Wescott
name: Jaffe, David
name: Jang, Eunji
name: Ji, Qingping
name: Jia, Sen
name: Jin, Yifan
name: Junkerkalefeld, Henrik
name: Kaleta, Mateusz Jakub
name: Kalita, Dibyajyoti
name: Basith Kaliyar, Abdul
name: Kandra, Jakub
name: Kang, Shuaiyan
name: Karyan, Gevorg
name: Kawasaki, Takeo
name: Keil, Felix
name: Kiesling, Christian
name: Kim, Cheolhun
name: Kim, Doris Yangsoo
name: Kim, Kyungho
name: Kim, Yongkyu
name: Kindo, Haruki
name: Kinoshita, Kay
name: Kodys, Peter
name: Koga, Taichiro
name: Kohani, Shahab
name: Kojima, Kazuki
name: Konno, Tomoyuki
name: Korobov, Alexandr
name: Korpar, Samo
name: Kovalenko, Evgeniy
name: Kowalewski, Robert
name: Kraetzschmar, Thomas Michael Gerd
name: Krizan, Peter
name: Krokovny, Pavel
name: Kuhr, Thomas
name: Kulii, Yaroslav
name: Kumar, Jitendra
name: Kumar, Manish
name: Kumara, Kospalage Janaka
name: Kunigo, Takuto
name: Kuzmin, Alexander
name: Kwon, Youngjoon
name: Lacaprara, Stefano
name: Lai, Yun-Tsung
name: Lalwani, Kavita
name: Lam, Tommy
name: Lanceri, Livio
name: Lange, Jens Soeren
name: Laurenza, Martina
name: Lautenbach, Klemens
name: Leboucher, Robin
name: Le Diberder, Francois Rene
name: Lee, MyeongJae
name: Leo, Paolo
name: Lemettais, Clotilde
name: Levit, Dmytro
name: Lewis, Peter
name: Li, Chunhua
name: Li, Longke
name: Li, Suxian
name: Li, Yang
name: Li, Yubo
name: Libby, James Frederick
name: Liptak, Zachary John
name: Liu, Meihong
name: Liu, Qingyuan
name: Liu, Yuxin
name: Liu, Zhiqing
name: Liventsev, Dmitri
name: Longo, Savino
name: Lueck, Thomas
name: Lyu, Chaoyi
name: Ma, Yue
name: Maggiora, Marco
name: Prabha Maharana, Swarna
name: Maiti, Rajesh Kumar
name: Maity, Souvik
name: Mancinelli, Giampiero
name: Manfredi, Riccardo
name: Manoni, Elisa
name: Mantovano, Michele
name: Marcantonio, Daniel
name: Marcello, Simonetta
name: Marinas, Carlos
name: Martellini, Cristina
name: Martini, Alberto
name: Martinov, Tommy
name: Massaccesi, Ludovico
name: Masuda, Masataka
name: Matsuoka, Kodai
name: Matvienko, Dmitry
name: Maurya, Shubhangi Krishan
name: McKenna, Janis Anne
name: Mehta, Rishabh
name: Meier, Frank
name: Merola, Mario
name: Metzner, Felix
name: Miller, Caleb
name: Mirra, Marco
name: Mitra, Sayan
name: Miyabayashi, Kenkichi
name: Miyake, Hideki
name: Mizuk, Roman
name: Mohanty, Gagan Bihari
name: Mondal, Suryanarayan
name: Moneta, Stefano
name: Moser, Hans-Guenther
name: Mrvar, Manca
name: Mussa, Roberto
name: Nakamura, Isamu
name: Nakamura, Katsuro
name: Nakao, Mikihiko
name: Nakazawa, Hideyuki
name: Nakazawa, Yu
name: Narimani Charan, Abtin
name: Naruki, Megumi
name: Narwal, Devender Kumar
name: Natkaniec, Zbigniew Marian
name: Natochii, Andrii
name: Nayak, Lopamudra
name: Nayak, Minakshi
name: Nazaryan, Gevorg
name: Neu, Marc
name: Niebuhr, Carsten
name: Ninkovic, Jelena
name: Nishida, Shohei
name: Novosel, Anja
name: Ogawa, Satoru
name: Onishchuk, Yuriy
name: Ono, Hiroaki
name: Otani, Fumiaki
name: Pakhlov, Pavel
name: Pakhlova, Galina
name: Panta, Anil
name: Pardi, Silvio
name: Parham, Katherine
name: Park, Hwanbae
name: Park, Seokhee
name: Paschen, Botho
name: Passeri, Antonio
name: Patra, Sourav
name: Pedlar, Todd Kristofer
name: Peschke, Richard
name: Pestotnik, Rok
name: Piccolo, Marcello
name: Piilonen, Leo
name: Pinna Angioni, Gian Luca
name: Podesta lerma, Pedro Luis Manuel
name: Podobnik, Tomaz
name: Pokharel, Saroj
name: Praz, Cyrille
name: Prell, Soeren
name: Prencipe, Elisabetta
name: Prim, Markus Tobias
name: Prudiiev, Ihor
name: Purwar, Harsh
name: Rados, Petar
name: Raeuber, Geraldine
name: Raiz, Sebastiano
name: Rauls, Noreen
name: Reif, Markus
name: Reiter, Simon
name: Remnev, Mikhail
name: Ripp-Baudot, Isabelle
name: Rizzo, Giuliana
name: Robertson, Steven H.
name: Roehrken, Markus
name: Roney, John Michael
name: Rostomyan, Armine
name: Rout, Niharika
name: Russo, Guido
name: Sanders, David Alan
name: Sandilya, Saurabh
name: Santelj, Luka
name: Sato, Yo
name: Savinov, Vladimir
name: Scavino, Bianca
name: Schmitt, Caspar
name: Schwanda, Christoph
name: Schwickardi, Marike
name: Seino, Yoshiaki
name: Selce, Andrea
name: Senyo, Katsumi
name: Serrano, Justine
name: Sevior, Martin Edmund
name: Sfienti, Concettina
name: Shan, Wei
name: Shi, Xiaodong
name: Shillington, Trevor
name: Shiu, Jing-Ge
name: Shtol, Dmitry
name: Shwartz, Boris
name: Sibidanov, Alexei
name: Simon, Frank
name: Singh, Jasbir
name: Skorupa, Justin
name: Sobie, Randall
name: Sobotzik, Martin
name: Soffer, Abner
name: Sokolov, Anatoly
name: Solovieva, Elena
name: Spataro, Stefano
name: Spruck, Bjoern
name: Staric, Marko
name: Stavroulakis, Petros
name: Stefkova, Slavomira
name: Stroili, Roberto
name: Sue, Yuki
name: Sumihama, Mizuki
name: Sumisawa, Kazutaka
name: Sutcliffe, William
name: Suwonjandee, Narumon
name: Svidras, Henrikas
name: Takahashi, Maiko
name: Takizawa, Makoto
name: Tamponi, Umberto
name: Tanaka, Shuji
name: Tanida, Kiyoshi
name: Tenchini, Francesco
name: Thaller, Arthur
name: Tittel, Oskar
name: Tiwary, Rahul
name: Tonelli, Diego
name: Torassa, Ezio
name: Trabelsi, Karim
name: Tsaklidis, Ilias
name: Uchida, Makoto
name: Ueda, Ikuo
name: Uglov, Timofey
name: Unger, Kai Lukas
name: Unno, Yuji
name: Uno, Kenta
name: Uno, Shoji
name: Urquijo, Phillip
name: Ushiroda, Yutaka
name: Vahsen, Sven Einar
name: van Tonder, Raynette
name: Varvell, Kevin Ernest
name: Veronesi, Michele
name: Vinokurova, Anna
name: V S, Vismaya
name: Vitale, Lorenzo
name: Vobbilisetti, Vidya Sagar
name: Volpe, Roberta
name: Wach, Benedikt
name: Wakai, Miho
name: Wallner, Stefan
name: Wang, Erfei
name: Wang, Min-Zu
name: Wang, Xiaolong
name: Wang, Zihan
name: Warburton, Andreas
name: Watanabe, Minori
name: Watanuki, Shun
name: Wessel, Christian
name: Won, Eunil
name: Xu, Xinping
name: Yabsley, Bruce Donald
name: Yamada, Satoru
name: Yan, Wenbiao
name: Yang, Seongbae
name: Yelton, John
name: Yin, Junhao
name: Yoshihara, Keisuke
name: Yuan, Changzheng
name: Yusa, Yosuke
name: Zani, Laura
name: Zeng, Fanli
name: Zhang, Boyang
name: Zhang, Yi
name: Zhilich, Victor
name: Zhou, Qi-Dong
name: Zhou, Xing-Yu
name: Zhukova, Valentina
name: Zlebcik, Radek
name: Belle-II Collaboration
Publisher: name: Deutsches Elektronen-Synchrotron, DESY, Hamburg
Year: 2024
Subjects: electron, momentum spectrum
muon, coupling
BELLE
universality
GeV
branching ratio
KEK-B
lepton
statistical

description: We present a measurement of the ratio $R_\mu = \mathcal{B}(\tau^-\to \mu^-\bar\nu_\mu\nu_\tau) / \mathcal{B}(\tau^-\to e^-\bar\nu_e\nu_\tau)$ of branching fractions $\mathcal{B}$ of the $\tau$ lepton decaying to muons or electrons using data collected with the Belle II detector at the SuperKEKB $e^+e^-$ collider. The sample has an integrated luminosity of 362 fb$^{-1}$ at a centre-of-mass energy of 10.58 GeV. Using an optimised event selection, a binned maximum likelihood fit is performed using the momentum spectra of the electron and muon candidates. The result, $R_\mu = 0.9675 \pm 0.0007 \pm 0.0036$, where the first uncertainty is statistical and the second is systematic, is the most precise to date. It provides a stringent test of the light-lepton universality, translating to a ratio of the couplings of the muon and electron to the $W$ boson in $\tau$ decays of $0.9974 \pm 0.0019$, in agreement with the standard model expectation of unity.