Direct measurement of the phi(1020) leptonic branching ratio

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

doi:10.1103/PhysRevLett.86.1698

Direct measurement of the phi(1020) leptonic branching ratio

Phys Rev Lett. 2001 Feb 26;86(9):1698-701. doi: 10.1103/PhysRevLett.86.1698.

Affiliation

¹ Budker Institute of Nuclear Physics and Novosibirsk State University, 630090, Novosibirsk, Russia.

PMID: 11290227
DOI: 10.1103/PhysRevLett.86.1698

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.