Study of the KS0KS0 final state in two-photon collisions

The reaction e+e− → e+e−γ∗γ∗ → e+e−KS0KS0 is studied with the L3 detector at LEP and the formation of the f2′(1525) resonance is observed. For an integrated luminosity of 114 pb−1, 31±6 f2′ events are found. Their angular distribution is consistent with a pure helicity two. The radiative width times the branching ratio is measured to be Γγγ(f2′)×Br(f2′ → KK)=(0.093±0.018±0.022) keV. Only three events are found in the f2(1270)−a2(1320) mass region, consistent with destructive f2−a2 interference in the KS0KS0 final state. The mixing angle of the tensor meson nonet is determined to the θ = (29.4−1.6+1.4)°.