Precision measurements of B[ψ(3686)→π+π-J/ψ] and B[J/ψ→l+l-]

Media type: E-Article

Title: Precision measurements of B[ψ(3686)→π+π-J/ψ] and B[J/ψ→l+l-]

Contributor: Ablikim, M. [Author]; Achasov, M. N. [Author]; Bennett, J. V. [Author]; Jing, F. F. [Author]; Kalantar-Nayestanaki, N. [Author]; Kavatsyuk, M. [Author]; Kloss, B. [Author]; Kopf, B. [Author]; Kornicer, M. [Author]; Kuehn, W. [Author]; Lai, W. [Author]; Lange, J. S. [Author]; Lara, M. [Author]; Bertani, M. [Author]; Larin, P. [Author]; Leyhe, M. [Author]; Li, C. H. [Author]; Li, Cheng [Author]; Li, Cui [Author]; Li, D. M. [Author]; Li, F. [Author]; Li, G. [Author]; Li, H. B. [Author]; Li, J. C. [Author]; [...]

imprint: Soc., 2013

Language: English

DOI: https://doi.org/10.1103/PhysRevD.88.032007

ISSN: 1550-2368; 1550-7998; 0556-2821; 1089-4918

Keywords: psi mesons: branching ratio: measured ; psi(3685) --> J/psi(3100) pi+ pi- ; 3.650: 3.686 GeV-cms ; experimental results ; J/psi(3100) --> lepton+ lepton- ; electron muon: universality ; Beijing Stor ; precision measurement ; electron positron: annihilation ; J/psi(3100): leptonic decay ; psi(3685): hadronic decay ; BES

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Description: Based on $(106.41 \pm 0.86)\times 10^{6}$ $\psi(3686)$ events collected with the BESIII detector at the BEPCII collider, the branching fractions of $\psi(3686) \to \pi^+\pi^- J/\psi$, $J/\psi \to e^+e^- $, and $J/\psi \to \mu^+\mu^-$ are measured. We obtain ${\cal B}[\psi(3686) \to \pi^+\pi^-J/\psi]=(34.98\pm 0.02\pm 0.45)%$, ${\cal B}[J/\psi \to e^+e^-] = (5.983 \pm 0.007 \pm 0.037)%$ and ${\cal B}[J/\psi \to \mu^+\mu^-] = (5.973 \pm 0.007 \pm 0.038)%$. The measurement of ${\cal B}[\psi(3686) \to \pi^{+}\pi^{-}J/\psi]$ confirms the CLEO-c measurement, and is apparently larger than the others. The measured $J/\psi$ leptonic decay branching fractions agree with previous experiments within one standard deviation. These results lead to ${\cal B}[J/\psi \to l^+l^-] = (5.978 \pm 0.005 \pm 0.040)%$ by averaging over the $e^{+}e^{-}$ and $\mu^{+}\mu^{-}$ channels and a ratio of ${\cal B}[J/\psi \to e^+e^-] / {\cal B}[J/\psi \to \mu^+\mu^-] = 1.0017 \pm 0.0017 \pm 0.0033$, which tests $e$-$\mu$ universality at the four tenths of a percent level. All the measurements presented in this paper are the most precise in the world to date.

Access State: Open Access

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