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arXiv · 1904.02440

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

Belle Collaboration·S. Wehle·I. Adachi·K. Adamczyk·H. Aihara·D. M. Asner·H. Atmacan·V. Aulchenko·T. Aushev·R. Ayad·V. Babu·P. Behera·M. Berger·V. Bhardwaj·J. Biswal·A. Bozek·M. Bračko·T. E. Browder·M. Campajola·L. Cao·M. -C. Chang·A. Chen·B. G. Cheon·K. Chilikin·K. Cho·Y. Choi·S. Choudhury·D. Cinabro·S. Cunliffe·N. Dash·G. De Nardo·F. Di Capua·S. Dubey·S. Eidelman·D. Epifanov·T. Ferber·B. G. Fulsom·R. Garg·V. Gaur·N. Gabyshev·A. Garmash·A. Giri·P. Goldenzweig·D. Greenwald·Y. Guan·J. Haba·O. Hartbrich·K. Hayasaka·H. Hayashii·M. T. Hedges·T. Higuchi·W. -S. Hou·C. -L. Hsu·T. Iijima·K. Inami·G. Inguglia·A. Ishikawa·R. Itoh·M. Iwasaki·Y. Iwasaki·W. W. Jacobs·S. Jia·Y. Jin·D. Joffe·J. Kahn·A. B. Kaliyar·G. Karyan·H. Kichimi·D. Y. Kim·K. T. Kim·S. H. Kim·Y. -K. Kim·K. Kinoshita·I. Komarov·S. Korpar·D. Kotchetkov·R. Kroeger·P. Krokovny·T. Kuhr·R. Kulasiri·R. Kumar·K. Kumara·A. Kuzmin·Y. -J. Kwon·J. S. Lange·J. Y. Lee·S. C. Lee·Y. B. Li·J. Libby·Z. Liptak·D. Liventsev·T. Luo·J. MacNaughton·M. Masuda·T. Matsuda·J. T. McNeil·M. Merola·F. Metzner·H. Miyata·R. Mizuk
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Abstract

We present a measurement of $R_{K^{\ast}}$, the branching fraction ratio ${{\cal B}(B\to K^\ast \mu^+ \mu^-)}$/ ${{\cal B}(B\to K^\ast e^+ e^-)}$, for both charged and neutral $B$ mesons. The ratio for the charged case, $R_{K{^{\ast +}}}$, is the first measurement ever performed. In addition, we report absolute branching fractions for the individual modes in bins of the squared dilepton invariant mass, $q^2$. 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 $e^+e^-$ collider. The obtained results are consistent with Standard Model expectations.

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Belle Collaboration, S. Wehle, I. Adachi, K. Adamczyk, H. Aihara, D. M. Asner, H. Atmacan, V. Aulchenko, T. Aushev, R. Ayad, V. Babu, P. Behera, M. Berger, V. Bhardwaj, J. Biswal, A. Bozek, M. Bračko, T. E. Browder, M. Campajola, L. Cao, M. -C. Chang, A. Chen, B. G. Cheon, K. Chilikin, K. Cho, Y. Choi, S. Choudhury, D. Cinabro, S. Cunliffe, N. Dash, G. De Nardo, F. Di Capua, S. Dubey, S. Eidelman, D. Epifanov, T. Ferber, B. G. Fulsom, R. Garg, V. Gaur, N. Gabyshev, A. Garmash, A. Giri, P. Goldenzweig, D. Greenwald, Y. Guan, J. Haba, O. Hartbrich, K. Hayasaka, H. Hayashii, M. T. Hedges, T. Higuchi, W. -S. Hou, C. -L. Hsu, T. Iijima, K. Inami, G. Inguglia, A. Ishikawa, R. Itoh, M. Iwasaki, Y. Iwasaki, W. W. Jacobs, S. Jia, Y. Jin, D. Joffe, J. Kahn, A. B. Kaliyar, G. Karyan, H. Kichimi, D. Y. Kim, K. T. Kim, S. H. Kim, Y. -K. Kim, K. Kinoshita, I. Komarov, S. Korpar, D. Kotchetkov, R. Kroeger, P. Krokovny, T. Kuhr, R. Kulasiri, R. Kumar, K. Kumara, A. Kuzmin, Y. -J. Kwon, J. S. Lange, J. Y. Lee, S. C. Lee, Y. B. Li, J. Libby, Z. Liptak, D. Liventsev, T. Luo, J. MacNaughton, M. Masuda, T. Matsuda, J. T. McNeil, M. Merola, F. Metzner, H. Miyata, R. Mizuk. 2019-04-04. Test of lepton-flavor universality in ${B\to K^\ast\ell^+\ell^-}$ decays at Belle. https://doi.org/10.1103/physrevlett.126.161801

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