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Published October 31, 2013 | Published + Submitted
Journal Article Open

Measurement of an excess of B→D^(*)τ^−ν_τ decays and implications for charged Higgs bosons


Based on the full BABAR data sample, we report improved measurements of the ratios R(D)=B(B→Dτ−ν_τ)/B(B→Dℓ−ν_ℓ) and R(D^∗)=B(B→D^∗τ−ν_τ)/B(B→D^∗ℓ−ν_ℓ), where ℓ refers to either an electron or muon. These ratios are sensitive to new physics contributions in the form of a charged Higgs boson. We measure R(D)=0.440±0.058±0.042 and R(D^∗)=0.332±0.024±0.018, which exceed the standard model expectations by 2.0σ and 2.7σ, respectively. Taken together, the results disagree with these expectations at the 3.4σ level. This excess cannot be explained by a charged Higgs boson in the type II two-Higgs-doublet model. Kinematic distributions presented here exclude large portions of the more general type III two-Higgs-doublet model, but there are solutions within this model compatible with the results.

Additional Information

© 2013 American Physical Society. Received 5 March 2013; published 31 October 2013. The concept for this analysis is to a large degree based on earlier BABAR work and we acknowledge the guidance provided by M. Mazur. The authors consulted with theorists A. Datta, S. Westhoff, S. Fajfer, J. Kamenik, and I. Nišandžić on the calculations of the charged Higgs contributions to the decay rates. We are grateful for the extraordinary contributions of our PEP-II colleagues in achieving the excellent luminosity and machine conditions that have made this work possible. The success of this project also relied critically on the expertise and dedication of the computing organizations that support BABAR. The collaborating institutions wish to thank SLAC for its support and the kind hospitality extended to them. This work is supported by the U.S. Department of Energy and National Science Foundation, the Natural Sciences and Engineering Research Council (Canada), the Commissariat à l'Energie Atomique and Institut National de Physique Nucléaire et de Physique des Particules (France), the Bundesministerium für Bildung und Forschung and Deutsche Forschungsgemeinschaft (Germany), the Istituto Nazionale di Fisica Nucleare (Italy), the Foundation for Fundamental Research on Matter (Netherlands), the Research Council of Norway, the Ministry of Education and Science of the Russian Federation, Ministerio de Economía y Competitividad (Spain), and the Science and Technology Facilities Council (United Kingdom). Individuals have received support from the Marie-Curie IEF program (European Union) and the A. P. Sloan Foundation (USA).

Attached Files

Published - PhysRevD.88.072012.pdf

Submitted - 1303.0571v1.pdf


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August 19, 2023
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