Light resonances in K⁰_SK^±π^± and ηπ⁺π^- final states in γγ collisions at LEP

Abstract

The e⁺e⁻→e⁺e^-K⁰_SK^±π^± and e⁺e⁻→e⁺e⁻ηπ ⁺π^- final states are studied with the L3 detector at LEP using data collected at centre-of-mass energies from 183 GeV up to 202 GeV. The mass spectrum of the K⁰_SK±π^± final state shows an enhancement around 1470 MeV, which is identified with the pseudoscalar meson η(1440). This state is observed in γγ collisions for the first time and its two-photon width is measured to be Γ_γγ(η(1440)) × BR(η(1440) → KK̅π) = 212±50(stat.)±23 (sys.) eV. Clear evidence is also obtained for the formation of the axial vector mesons f1(1420) and f1(1285). In the ηπ ⁺π^- channel the f₁(1285) is observed, and upper limits for the formation of η(1440) and η(1295) are obtained.