3 years ago

# Measurement of $\Gamma_{ee}\times\mathcal{B}_{\mu\mu}$ for $\psi(2S)$ meson.

I. I. Morozov, V. F. Kulikov, A. E. Bondar, A. A. Krasnov, A. R. Buzykaev, A. K. Barladyan, E. A. Kravchenko, A. L. Maslennikov, S. V. Karpov, A. M. Batrakov, A. V. Bobrov, V. A. Kiselev, K. Yu. Karukina, S. A. Kononov, D. N. Grigoriev, E. A. Kuper, A. V. Bogomyagkov, V. S. Bobrovnikov, D. A. Maksimov, I. A. Morozov, V. V. Kolmogorov, D. P. Kashtankin, S. E. Baru, S. I. Eidelman, S. I. Mishnev, O. I. Meshkov, V. M. Malyshev, G. V. Karpov, A. E. Blinov, V. L. Dorohov, E. M. Baldin, A. Yu. Barnyakov, V. N. Kudryavtsev, S. E. Karnaev, S. A. Glukhov, I. Yu. Basok, G. N. Baranov, E. A. Bekhtenev, V. V. Anashin, K. Yu. Kotov, V. M. Aulchenko, M. Yu. Barnyakov, P. B. Cheplakov, N. Yu. Muchnoi, E. B. Levichev, T. A. Kharlamova, S. A. Nikitin, I. A. Kuyanov, V. E. Blinov, G. Ya. Kurkin, O. V. Anchugov

The product of the electronic width of the $\psi(2S)$ meson and the branching fraction of its decay to the muon pair was measured in the $e^{+}e^{-} \to \psi(2S) \to \mu^{+}\mu^{-}$ process using nine data sets corresponding to an integrated luminosity of about 6.5 pb$^{-1}$ collected with the KEDR detector at the VEPP-4M electron-positron collider: $\Gamma_{ee}\times\mathcal{B}_{\mu\mu} = 19.3 \pm 0.3 \pm 0.5 ~\text{eV}.$ Adding the previous KEDR results on hadronic and leptonic channels, the values of the $\psi(2S)$ electronic width were obtained under two assumptions: either with the assumption of lepton universality $\Gamma_{ee} = 2.279 \pm 0.015 \pm 0.042 ~\text{keV}$ or without it, summing up hadronic and three independent leptonic channels: $\Gamma_{ee} = 2.282 \pm 0.015 \pm 0.042 ~\text{keV}.$

Publisher URL: http://arxiv.org/abs/1801.10362

DOI: arXiv:1801.10362v1

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