Direct measurement of the phi(1020) leptonic branching ratio.

Authors :: Achasov MN
Beloborodov KI
Berdyugin AV
Bogdanchikov AG
Bozhenok AV
Bukin AD
Bukin DA
Burdin SV
Dimova TV
Drozdetsky AA
Druzhinin VP
Dubrovin MS
Gaponenko IA
Golubev VB
Ivanchenko VN
Ivanov PM
Korol AA
Koshuba SV
Lysenko AP
Nesterenko IN
Pakhtusova EV
Perevedentsev EA
Salnikov AA
Serednyakov SI
Shary VV
Shatunov YM
Sidorov VA
Silagadze ZK
Skrinsky AN
Usov YV
Vasiljev AV
Source :: Physical review letters [Phys Rev Lett] 2001 Feb 26; Vol. 86 (9), pp. 1698-701.
Publication Year :: 2001
Abstract: 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.