Study of the KS 0KS 0 final state in two-photon collisions

The reaction e + e − →e + e − γ∗γ∗→e + e − K 0 S K 0 S is studied with the L3 detector at LEP and the formation of the f 2 '(1525) resonance is observed. For an integrated luminosity of 114 pb −1 , 31±6 f 2 ' events are found. Their angular distribution is consistent with a pure helicity two. The radiative width times the branching ratio is measured to be Γ γγ (f' 2 ) × (Br((f' 2 → KK)keV. Only three events are found in the f2(1270)-a2(1320) mass region, consistent with destructive f 2 -a 2 interference in the K S 0 K S 0 final state. The mixing angle of the tensor meson nonet is determined to the θ = (29.4 −1.6 +1.4 )±.