A study of γ γ → KS 0 KS 0 production at energies from 2.4 to 4.0 GeV at Belle

KS 0 KS 0 production in two-photon collisions has been studied using a 397.6 fb-1 data sample collected with the Belle detector at the KEKB e+ e- collider. For the first time the cross sections are measured in the two-photon center-of-mass energy range between 2.4 GeV and 4.0 GeV and angular range | cos θ* | < 0.6. Combining the results with measurements of γ γ → K+ K- from Belle, we observe that the cross section ratio σ (KS 0 KS 0) / σ (K+ K-) decreases from ∼0.13 to ∼0.01 with increasing energy. Signals for the χc 0 and χc 2 charmonium states are also observed. © 2007 Elsevier B.V. All rights reserved.