# Test of lepton flavor universality in ${B\to K^\ast\ell^+\ell^-}$ decays at Belle

@article{Abdesselam2019TestOL, title={Test of lepton flavor universality in \$\{B\to K^\ast\ell^+\ell^-\}\$ decays at Belle}, author={Belle Collaboration A. Abdesselam and Iki Adachi and Karol Adamczyk and J. K. Ahn and Hiroaki Aihara and S. al Said and K. Arinstein and Y. Arita and David Asner and H. Atmacan and Vladimir M. Aulchenko and T. A Kh Aushev and R. Ayad and Tariq Aziz and V. Babu and I. Badhrees and Seema Bahinipati and Andrew Bakich and Yifang Ban and Vikas Bansal and Elisabetta Luigia Barberio and Matthew Barrett and W. Bartel and Prafulla Kumar Behera and C. Bele{\~n}o and Konstantin Belous and Massimo Berger and Florian Urs Bernlochner and David Z. Besson and V. Bhardwaj and Bipul Bhuyan and Tadeas Bilka and Jyoti Prakash Biswal and T. Bloomfield and A. Bobrov and Alexander E. Bondar and G. Bonvicini and Andrz{\'e}j Bozek and M. Bravcko and Nils Braun and F. Breibeck and T. E. Browder and Marcello Campajola and L. Cao and Giacomo Caria and D. vCervenkov and M. C. Chang and P Chang and Yuan Chao and Racha Cheaib and Vladimir Chekelian and A. A. Chen and K.F. Chen and Byung Gu Cheon and Kirill Chilikin and R. Chistov and H. -E. Cho and K. Cho and Veronika Georgieva Chobanova and S-K. Choi and Y. K. Choi and Somnath Choudhury and David Anthony Cinabro and Jason D. Crnkovic and Samuel Cunliffe and Thomas Czank and M. Danilov and N. Dash and Salvatore Di Carlo and Jochen Dingfelder and Z. Dolevzal and Thanh Van Dong and David Dossett and Z. Dr'asal and Alexey Drutskoy and S. Dubey and Deepanwita Dutta and Semen Eidelman and Denis Epifanov and James E. Fast and Michael Feindt and Torben Ferber and A. Frey and Oliver Frost and B. G. Fulsom and Rocky Bala Garg and Vinod K. Gaur and N. I. Gabyshev and Alexey Garmash and Moritz Gelb and Jochen Gemmler and D. Getzkow and Francesca Giordano and Anjan Kumar Giri and Pablo D. Goldenzweig and Bo{\vs}tjan Golob and Daniel Greenwald and M. Grosse Perdekamp and Jan Grygier and Olga Grzymkowska and Y. Guan and Elisa Guido and H. Guo and Junji Haba and P. Hamer and Kazuhiro Hara and T. Hara and Yoji Hasegawa and Jan Hasenbusch and K. Hayasaka and Hisaki Hayashii and X. H. He and M. Heck and Morgan Hedges and Dale Heffernan and Manuel Heider and Aaron Heller and Takuya Higuchi and Shigeki Hirose and Tsuyoshi Horiguchi and Yoichi Hoshi and Kotoyo Hoshina and Wei-Shu Hou and Y. Hsiung and C-L. Hsu and K. Huang and M. Huschle and Y. Igarashi and Toru Iijima and M. Imamura and Kenji Inami and Gianluca Inguglia and Akira Ishikawa and Kiyoshi Itagaki and Ryosuke Itoh and M. Iwasaki and Yoh Iwasaki and S. Iwata and William W. Jacobs and Igal Jaegl{\'e} and Hyejin Jeon and Sen Jia and Y. Jin and David Noah Joffe and M Jones and Changwoo Joo and Kyung Kwang Joo and T. Julius and James Kahn and Hidekazu Kakuno and A. B. Kaliyar and J. H. Kang and Kookjin Kang and Peter Kapusta and Gevorg Karyan and Satoru Kataoka and Eriko Kato and Yukihiro Kato and P. Katrenko and Hikaru Kawai and Toshisuke Kawasaki and Thomas Keck and Hiromichi Kichimi and Ch. Kiesling and B. H. Kim and C. H. Kim and D. Y. Kim and H. J. Kim and H.‐J. Kim and J. B. Kim and K. T. Kim and S. H. Kim and S. K. Kim and Y. J. Kim and T. D. Kimmel and Haruki Kindo and K. Kinoshita and Claus Kleinwort and J. Klucar and Naoki Kobayashi and P. Kodyvs and Y. Koga and Tomohiro Konno and Samo Korpar and Dmitri Kotchetkov and Richard T. Kouzes and Peter Krivzan and Robert Kroeger and J. F. Krohn and Pavel Krokovny and Belle Collaboration B. Kronenbitter and Thomas Kuhr and Ratnappuli L. Kulasiri and R. Kumar and Tetsuro Kumita and Eiji Kurihara and Yoko Kuroki and A. Kuzmin and P. Kvasnivcka and Young Jae Kwon and Y.-T. Lai and Kavita Lalwani and J. S. Lange and I. S. Lee and J. K. P. Lee and J. Y. Lee and S. C. Lee and Martin Leitgab and Rupert Leitner and Dmytro Levit and Philip Lewis and C. H. Li and H. B. Li and L. K. Li and Y. B. Li and Y. B. Li and L. Li Gioi and James F. Libby and Kilian Lieret and Antonio Limosani and Z. Liptak and C. Y. Liu and Y. Liu and D. Liventsev and Alyssa Loos and Remi L{\'e}andre Albert Louvot and P. Lu and Matic Lubej and Tao Luo and Jane Macnaughton and M. Masuda and Takeshi Matsuda and D. Matvienko and J. T. McNeil and Mario Merola and Franka Metzner and Yoshinari Mikami and Kenkichi Miyabayashi and Yoshiyuki Miyachi and Hideki Miyake and Hitoshi Miyata and Yoshiharu Miyazaki and R. Mizuk and G. B. Mohanty and Soumya Mohanty and H. K. Moon and T. Moon and Taiki Mori and T. Morii and H-G. Moser and Manca Mrvar and Th. Muller and N. Muramatsu and Roberto Mussa and Y. Nagasaka and Yu Nakahama and Isamu Nakamura and K. Nakamura and Eiichi Nakano and H. Nakano and Toshiyuki Nakano and M. Nakao and H. Nakayama and Hideyuki Nakazawa and Tara Nanut and Kamal Jyoti Nath and Zbigniew Natkaniec and M. Nayak and Kazushi Neichi and C. R. Ng and Carsten Niebuhr and Masayuki Niiyama and Numan Nisar and Shin'ya Nishida and Kurtis Alan Nishimura and Osamu Nitoh and Akira Ogawa and K. Ogawa and Satoru Ogawa and Takayoshi Ohshima and Senji Okuno and Stephen Lars Olsen and Hiroaki Ono and Yoshimasa Ono and Y. Onuki and Waclaw Ostrowicz and Christian Oswald and H. Ozaki and P. Pakhlov and Galina Pakhlova and Bilas Kanti Pal and E. Panzenbock and Silvio Pardi and C.-S. Park and C. W. Park and H. K. Park and K. S. Park and Sheong Hwan Park and S. Patra and Soumen Paul and I. Pavelkin and Todd Kristofer Pedlar and T. Peng and L. Pes'antez and Rok Pestotnik and Marco Peters and Leo Piilonen and Valentin L. Popov and Kodassery Prasanth and Elisabetta Prencipe and Markus Tobias Prim and Kolja Prothmann and M. V. Purohit and A. Rabusov and Johannes Rauch and Burkard C. Reisert and Philo Resmi and E. Ribevzl and Martin Ritter and Jamal Rorie and Armine Armand Rostomyan and Maria Barbara R{\'o}żańska and Steve R. Rummel and Guido Russo and Deepak Kumar Sahoo and Himansu Sahoo and T. Saito and Yoshihide Sakai and Marzieh Salehi and S. Sandilya and Daniel Santel and Luka {\vS}antelj and Tomoyuki Sanuki and Junya Sasaki and Noboru Sasao and Y. Sato and Vladimir Savinov and T. Schluter and O. Schneider and G. Schnell and P. Schonmeier and Miranda T. Schram and J. Schueler and C. Schwanda and Alan Jay Schwartz and B. Schwenker and Ralf Seidl and Yoshiaki Seino and Denis Semmler and Katsumi Senyo and Oksu Seon and Ihn Sik Seong and M. E. Sevior and Lei Shang and Mikhail Shapkin and V. E. Shebalin and C. P. Shen and T. A. Shibata and Hiroshi Shibuya and Satoru Shinomiya and J. -G. Shiu and Boris A. Shwartz and A. Sibidanov and Frank Simon and J. B. Singh and R. Sinha and K. M. Smith and Alexei Sokolov and Yu. V. Soloviev and Elena Solovieva and Samo Stanivc and M. Starivc and Michael Steder and Zachary Stottler and Jan Strube and Jacek Stypuła and Shinichi Sugihara and Akira Sugiyama and Mizuki Sumihama and Kazutaka Sumisawa and Takayuki Sumiyoshi and William Lawrence Sutcliffe and K. Suzuki and S. Suzuki and S. Suzuki and Z. Suzuki and Hisashi Takeichi and Makoto Takizawa and Umberto Tamponi and M. Tanaka and S. Tanaka and Kiyoshi Tanida and Nanae Taniguchi and Y. R. Tao and G. N. Taylor and Francesco Tenchini and Y. Teramoto and Karim Trabelsi and Tohru Tsuboyama and Masaki Uchida and Toyoaki Uchida and I. Ueda and Sadaharu Uehara and Timofey Uglov and Yoshinobu Unno and Shoji Uno and Phillip Urquijo and Yutaka Ushiroda and Yu. V. Usov and Sven E. Vahsen and Charlotte Barbara Van Hulse and Raynette van Tonder and Pit Vanhoefer and G. S. Varner and Kevin Varvell and Kim Vervink and Anna Viktorovna Vinokurova and Vitaly Vorobyev and A. Vossen and M. N. Wagner and E. Waheed and B. Q. Wang and C. Wang and M.-Z. Wang and P. Wang and X. L. Wang and M. Watanabe and Y. X. Watanabe and Shoichi Watanuki and R. W. J. Wedd and S. Wehle and Eberhard Widmann and Jaroslaw Pawel Wiechczynski and K. M. Williams and Eunil Won and Bruce Yabsley and Sumio Yamada and H. Yamamoto and Yusuke Yamashita and S. B. Yang and Sergey Yashchenko and H Y Ye and J. Yelton and J. H. Yin and Youngmin Yook and Chang-Zheng Yuan and Yosuke Yusa and S. Zakharov and C C Zhang and J. J. Zhang and L. Zhang and Z. P. Zhang and L. Zhao and V. N. Zhilich and Victoria Zhukova and Vladimir Zhulanov and Tomi Živko and An{\vz}e Zupanc and N. Zwahlen}, journal={arXiv: High Energy Physics - Experiment}, year={2019} }

We present a measurement of $R_{K^{\ast}}$, the ratio of the branching fractions ${\cal B}(B\to K^\ast \mu^+ \mu^-)$ and ${\cal B}(B\to K^\ast e^+ e^-)$, for both charged and neutral $B$ mesons. The ratio for charged $B$ mesons, $R_{K{^{\ast +}}}$, is the first measurement ever performed. The analysis is based on a data sample of $711~\mathrm{fb}^{-1}$, containing $772\times 10^{6}$ $B\bar B$ events, recorded at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy…

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