A study of γγ→KS0KS0 production at energies from 2.4 to 4.0 GeV at Belle

KS0KS0 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 |cosθ∗|<0.6. Combining the results with measurements of γγ→K+K− from Belle, we observe that the cross section ratio σ(KS0KS0)/σ(K+K−) decreases from ∼0.13 to ∼0.01 with increasing energy. Signals for the χc0 and χc2 charmonium states are also observed.