Light resonances in K<SUP>0</SUP><SUB>S</SUB>K±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 γ γ collisions for the first time and its two-photon width is measured to be Γγ γ (η(1440)) × BR(η(1440) → KKπ ) = 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.