Faculty and Student Publications

Authors

G. Caria, University of Melbourne
P. Urquijo, University of Melbourne
I. Adachi, The Graduate University for Advanced Studies
H. Aihara, The University of Tokyo
S. Al Said, King Abdulaziz University
D. M. Asner, Brookhaven National Laboratory
H. Atmacan, University of South Carolina
T. Aushev, Moscow Institute of Physics and Technology
V. Babu, Deutsches Elektronen-Synchrotron (DESY)
I. Badhrees, King Abdulaziz City for Science and Technology
S. Bahinipati, Indian Institute of Technology Bhubaneswar
A. M. Bakich, The University of Sydney
P. Behera, Indian Institute of Technology Madras
C. Beleño, Universität Göttingen
J. Bennett, University of Mississippi
B. Bhuyan, Indian Institute of Technology Guwahati
T. Bilka, Charles University
J. Biswal, Jozef Stefan Institute
A. Bozek, Henryk Niewodniczanski Institute of Nuclear Physics of the Polish Academy of Sciences
M. Bračko, Jozef Stefan Institute
T. E. Browder, University of Hawaiʻi at Mānoa
M. Campajola, Istituto Nazionale di Fisica Nucleare, Sezione di Napoli
D. Červenkov, Charles University
P. Chang, National Taiwan University
R. Cheaib, University of Mississippi
V. Chekelian, Max Planck Institute for Physics (Werner Heisenberg Institute)
A. Chen, National Central University Taiwan
B. G. Cheon, Hanyang University
K. Chilikin, P.N. Lebedev Physical Institute of the Russian Academy of Sciences
H. E. Cho, Hanyang University
K. Cho, Korea Institute of Science and Technology Information
Y. Choi, Sungkyunkwan University

Document Type

Article

Publication Date

4-24-2020

Abstract

© 2020 authors. The experimental results on the ratios of branching fractions R(D)=B(B→Dτ-ντ)/B(B→Dℓ-νℓ) and R(D∗)=B(B→D∗τ-ντ)/B(B→D∗ℓ-νℓ), where ℓ denotes an electron or a muon, show a long-standing discrepancy with the standard model predictions, and might hint at a violation of lepton flavor universality. We report a new simultaneous measurement of R(D) and R(D∗), based on a data sample containing 772×106 BB events recorded at the ϒ(4S) resonance with the Belle detector at the KEKB e+e- collider. In this analysis the tag-side B meson is reconstructed in a semileptonic decay mode and the signal-side τ is reconstructed in a purely leptonic decay. The measured values are R(D)=0.307±0.037±0.016 and R(D∗)=0.283±0.018±0.014, where the first uncertainties are statistical and the second are systematic. These results are in agreement with the standard model predictions within 0.2, 1.1, and 0.8 standard deviations for R(D), R(D∗), and their combination, respectively. This work constitutes the most precise measurements of R(D) and R(D∗) performed to date as well as the first result for R(D) based on a semileptonic tagging method.

Relational Format

journal article

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