Direct measurement of the phi(1020) leptonic branching ratio.
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.
Achasov
M N
MN
Budker Institute of Nuclear Physics and Novosibirsk State University, 630090, Novosibirsk, Russia.
Beloborodov
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Berdyugin
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Bogdanchikov
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Bozhenok
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Bukin
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Bukin
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Burdin
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Dimova
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Drozdetsky
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Druzhinin
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Dubrovin
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Gaponenko
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Golubev
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Ivanchenko
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Ivanov
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Korol
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Koshuba
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Lysenko
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Nesterenko
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Pakhtusova
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Perevedentsev
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Salnikov
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Serednyakov
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Shary
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Shatunov
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Sidorov
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Silagadze
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Skrinsky
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Usov
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Vasiljev
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