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Published March 1, 2015 | Published + Submitted
Journal Article Open

Measurement of the D^0→π^−e^+ν_e differential decay branching fraction as a function of q^2 and study of form factor parametrizations


Based on a sample of 500 million e^+e^−→cc events recorded by the BABAR detector at c.m. energies of close to 10.6 GeV, we report on a study of the decay D^0→π^−e^+ν_e. We measure the ratio of branching fractions, R_D=B(D^0→π^−e^+ν_e)/B(D^0→K^−π^+)=0.0713±0.0017_(stat)±0.0024_(syst), and use the present world average for B(D^0→K^−π^+) to obtain B(D^0→π^−e^+ν_e)= 2.770±0.068_(stat)±0.092_(syst)±0.037_(ext))×10^(−3) where the third error accounts for the uncertainty on the branching fraction for the reference channel. The measured dependence of the differential branching fraction on q^2, the four-momentum transfer squared between the D and the π meson, is compared to various theoretical predictions for the hadronic form factor, f^π_+,D(q^2), and the normalization V_(cd)|×f^π_+,D(q^2=0)=0.1374±0.0038_(stat)±0.0022_(syst)±0.0009_(ext). is extracted from a fit to data. Using the most recent LQCD prediction of f^π_(+,D)(q^2=0)=0.666±0.029, we obtain |V_(cd)|=0.206±0.007_(exp)±0.009_(LQCD). Assuming, instead, |V_(cd)|=|V_(us)|=0.2252±0.0009, we obtain f^π_(+,D)(q^2=0)=0.610±0.020_(exp)±0.005_(ext). The q^2 dependence of f^π_(+,D)(q^2) is compared to a variety of multipole parametrizations. This information is applied to B^0→π^−e^+ν_e decays and, combined with an earlier B^0→π^−e^+ν_e measurement by BABAR, is used to derive estimates of |V_(ub)|.

Additional Information

© 2015 American Physical Society. Received 22 December 2014; published 31 March 2015. The authors wish to thank D. Becirevic, S. Descotes-Genon, and A. Le Yaouanc for their help with the theoretical interpretation of these results. 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 relies 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 US 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 (The Netherlands), the Research Council of Norway, the Ministry of Education and Science of the Russian Federation, Ministerio de Economía y Competitividad (Spain), the Science and Technology Facilities Council (United Kingdom), and the Binational Science Foundation (U.S.-Israel). Individuals have received support from the Marie-Curie IEF program (European Union) and the A. P. Sloan Foundation (USA).

Attached Files

Published - PhysRevD.91.052022.pdf

Submitted - 1412.5502v1.pdf


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