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  • Direct measurement of the p...
    Achasov, M N; Beloborodov, K I; Berdyugin, A V; Bogdanchikov, A G; Bozhenok, A V; Bukin, A D; Bukin, D A; Burdin, S V; Dimova, T V; Drozdetsky, A A; Druzhinin, V P; Dubrovin, M S; Gaponenko, I A; Golubev, V B; Ivanchenko, V N; Ivanov, P M; Korol, A A; Koshuba, S V; Lysenko, A P; Nesterenko, I N; Pakhtusova, E V; Perevedentsev, E A; Salnikov, A A; Serednyakov, S I; Shary, V V; Shatunov, Y M; Sidorov, V A; Silagadze, Z K; Skrinsky, A N; Usov, Y V; Vasiljev, A V

    Physical review letters, 02/2001, Letnik: 86, Številka: 9
    Journal Article

    The process e(+)e(-)-->mu(+)mu(-) has been studied by the SND detector at the VEPP-2M e(+)e(-) collider in the phi(1020)-resonance energy region. The measured effective phi meson leptonic branching ratio B(phi-->l(+)l(-)) identical with square root of B(phi-->e(+)e(-))B(phi-->mu(+)mu(-)) = (2.89 +/- 0.10 +/- 0.06) x 10(-4) agrees well with the Particle Data Group value B(phi-->e(+)e(-)) = (2.91 +/- 0.07) x 10(-4), confirming mu-e universality. Without additional assumption of mu-e universality the branching ratio B(phi-->mu(+)mu(-)) = (2.87 +/- 0.20 +/- 0.14) x 10(-4) was obtained.