Study of resonance formation in the mass region 1400−1500MeV through the reaction γγ→K⁰_SK^±π∓

Abstract

The K⁰_SK^±π∓ final state in two-photon collisions is studied with the L3 detector at LEP at e+e− centre-of-mass energies from 183 to 209 GeV with an integrated luminosity of 664.6 pb⁻¹. The η (1475) and f₁(1420) mesons are observed and their contribution is separated by measuring the formation rates as a function of the photon virtuality Q². The η (1475) is found to be dominant for Q² ≤ 0.01 GeV² and its two-photon width is measured to be 0.23±0.05 (stat.) ±0.05 (sys.) keV. At higher Q², the f⁻¹(1420) is formed and decays to K*(892)K. The γγ coupling and form factor parameters of this state are measured to be Γγγ = 3.2 ± 0.6 (stat.) ± 0.7 (sys.) keV and Λ₁ = 926 ± 72 (stat.) ± 32 (sys.) MeV, respectively.