Observation of the leptonic decay $D^+ \to τ^+ ν_τ$
Creators: name: BESIII Collaboration
name: Ablikim, M.
name: Achasov, M. N.
name: Adlarson, P.
name: Ahmed, S.
name: Albrecht, M.
name: Alekseev, M.
name: Amoroso, A.
name: An, F. F.
name: An, Q.
name: Bai, Y.
name: Bakina, O.
name: Ferroli, R. Baldini
name: Balossino, I.
name: Ban, Y.
name: Begzsuren, K.
name: Bennett, J. V.
name: Berger, N.
name: Bertani, M.
name: Bettoni, D.
name: Bianchi, F.
name: Biernat, J
name: Bloms, J.
name: Boyko, I.
name: Briere, R. A.
name: Cai, H.
name: Cai, X.
name: Calcaterra, A.
name: Cao, G. F.
name: Cao, N.
name: Cetin, S. A.
name: Chai, J.
name: Chang, J. F.
name: Chang, W. L.
name: Chelkov, G.
name: Chen, D. Y.
name: Chen, G.
name: Chen, H. S.
name: Chen, J. C.
name: Chen, M. L.
name: Chen, S. J.
name: Chen, Y. B.
name: Cheng, W.
name: Cibinetto, G.
name: Cossio, F.
name: Cui, X. F.
name: Dai, H. L.
name: Dai, J. P.
name: Dai, X. C.
name: Dbeyssi, A.
name: Dedovich, D.
name: Deng, Z. Y.
name: Denig, A.
name: Denysenko, I.
name: Destefanis, M.
name: De Mori, F.
name: Ding, Y.
name: Dong, C.
name: Dong, J.
name: Dong, L. Y.
name: Dong, M. Y.
name: Dou, Z. L.
name: Du, S. X.
name: Fan, J. Z.
name: Fang, J.
name: Fang, S. S.
name: Fang, Y.
name: Farinelli, R.
name: Fava, L.
name: Feldbauer, F.
name: Felici, G.
name: Feng, C. Q.
name: Fritsch, M.
name: Fu, C. D.
name: Fu, Y.
name: Gao, Q.
name: Gao, X. L.
name: Gao, Y.
name: Gao, Y.
name: Gao, Y. G.
name: Gao, Z.
name: Garillon, B.
name: Garzia, I.
name: Gersabeck, E. M.
name: Gilman, A.
name: Goetzen, K.
name: Gong, L.
name: Gong, W. X.
name: Gradl, W.
name: Greco, M.
name: Gu, L. M.
name: Gu, M. H.
name: Gu, S.
name: Gu, Y. T.
name: Guo, A. Q.
name: Guo, L. B.
name: Guo, R. P.
name: Guo, Y. P.
name: Guskov, A.
name: Han, S.
name: Hao, X. Q.
name: Harris, F. A.
name: He, K. L.
name: Heinsius, F. H.
name: Held, T.
name: Heng, Y. K.
name: Himmelreich, M.
name: Hou, Y. R.
name: Hou, Z. L.
name: Hu, H. M.
name: Hu, J. F.
name: Hu, T.
name: Hu, Y.
name: Huang, G. S.
name: Huang, J. S.
name: Huang, X. T.
name: Huang, X. Z.
name: Huesken, N.
name: Hussain, T.
name: Andersson, W. Ikegami
name: Imoehl, W.
name: Irshad, M.
name: Ji, Q.
name: Ji, Q. P.
name: Ji, X. B.
name: Ji, X. L.
name: Jiang, H. L.
name: Jiang, X. S.
name: Jiang, X. Y.
name: Jiao, J. B.
name: Jiao, Z.
name: Jin, D. P.
name: Jin, S.
name: Jin, Y.
name: Johansson, T.
name: Kalantar-Nayestanaki, N.
name: Kang, X. S.
name: Kappert, R.
name: Kavatsyuk, M.
name: Ke, B. C.
name: Keshk, I. K.
name: Khoukaz, A.
name: Kiese, P.
name: Kiuchi, R.
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name: Koch, L.
name: Kolcu, O. B.
name: Kopf, B.
name: Kuemmel, M.
name: Kuessner, M.
name: Kupsc, A.
name: Kurth, M.
name: Kurth, M. G.
name: Kühn, W.
name: Lange, J. S.
name: Larin, P.
name: Lavezzi, L.
name: Leithoff, H.
name: Lenz, T.
name: Li, C.
name: Li, Cheng
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name: Li, Ke
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name: Li, X. H.
name: Li, X. L.
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name: Li, Z. B.
name: Li, Z. Y.
name: Liang, H.
name: Liang, H.
name: Liang, Y. F.
name: Liang, Y. T.
name: Liao, G. R.
name: Liao, L. Z.
name: Libby, J.
name: Lin, C. X.
name: Lin, D. X.
name: Lin, Y. J.
name: Liu, B.
name: Liu, B. J.
name: Liu, C. X.
name: Liu, D.
name: Liu, D. Y.
name: Liu, F. H.
name: Liu, Fang
name: Liu, Feng
name: Liu, H. B.
name: Liu, H. M.
name: Liu, Huanhuan
name: Liu, Huihui
name: Liu, J. B.
name: Liu, J. Y.
name: Liu, K. Y.
name: Liu, Ke
name: Liu, L. Y.
name: Liu, Q.
name: Liu, S. B.
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name: Liu, X.
name: Liu, X. Y.
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name: Liu, Z. A.
name: Liu, Zhiqing
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name: Marcello, S.
name: Meng, Z. X.
name: Messchendorp, J. G.
name: Mezzadri, G.
name: Min, J.
name: Min, T. J.
name: Mitchell, R. E.
name: Mo, X. H.
name: Mo, Y. J.
name: Morales, C. Morales
name: Muchnoi, N. Yu.
name: Muramatsu, H.
name: Mustafa, A.
name: Nakhoul, S.
name: Nefedov, Y.
name: Nerling, F.
name: Nikolaev, I. B.
name: Ning, Z.
name: Nisar, S.
name: Niu, S. L.
name: Olsen, S. L.
name: Ouyang, Q.
name: Pacetti, S.
name: Pan, Y.
name: Papenbrock, M.
name: Patteri, P.
name: Pelizaeus, M.
name: Peng, H. P.
name: Peters, K.
name: Pettersson, J.
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name: Ping, R. G.
name: Pitka, A.
name: Poling, R.
name: Prasad, V.
name: Qi, H. R.
name: Qi, M.
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name: Weber, T.
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name: Wilkinson, G.
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name: Zafar, A. A.
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name: Zhang, T. J.
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name: Zhang, Y. T.
name: Zhang, Yang
name: Zhang, Yao
name: Zhang, Yi
name: Zhang, Yu
name: Zhang, Z. H.
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name: Zhao, G.
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name: Zhou, Xu
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Publisher: name: arXiv
Year: 2019
Subjects: subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: We report the first observation of $D^+\toτ^+ν_τ$ with a significance of $5.1σ$. We measure ${\cal B}(D^+\toτ^+ν_τ) = (1.20\pm0.24_{\text{stat.}}\pm0.12_{\text{syst.}})\times10^{-3}$. Taking the world average ${\cal B}(D^+\toμ^+ν_μ) = (3.74\pm0.17)\times10^{-4}$, we obtain $R_{τ/μ} =Γ(D^+\toτ^+ν_τ)/Γ(D^+\toμ^+ν_μ) = 3.21\pm0.64_{\text{stat.}}\pm0.43_{\text{syst.}}$, which is consistent with the Standard Model expectation of lepton flavor universality. Using external inputs, our results give values for the $D^+$ decay constant $f_{D^+}$ and the CKM matrix element $|V_{cd}|$ that are consistent with, but less precise than, other determinations.
description: 8 pages, 3 figures, as published