High-statistics study of $K^0_S K^0_S$ pair production in two-photon collisionsUehara, S. (Avtor) Bračko, Marko (Avtor) Golob, Boštjan (Avtor) Klučar, Jure (Avtor) Korpar, Samo (Avtor) Križan, Peter (Avtor) Pestotnik, Rok (Avtor) Petrič, Marko (Avtor) Starič, Marko (Avtor) Šantelj, Luka (Avtor) Zupanc, Anže (Avtor) C00C05C07C21quantum chromodynamicsquark modelparticle propertieslepton collider experimentsexperimental particle physicsWe report a high-statistics measurement of the differential cross section of the process $\gamma \gamma \to K^0_S K^0_S$ in the range $1.05\,{\mathrm {GeV}} \leq W \leq 4.00$ , where W is the center-of-mass energy of the colliding photons, using 972 $^{-1}$ of data collected with the Belle detector at the KEKB asymmetric-energy e+e− collider operated at and near the $\Upsilon$-resonance region. The differential cross section is fitted by parameterized S-, $D_0$, $D_2$-, $G_0$-, and $G_2$-wave amplitudes. In the $D_2$ wave, the $f_2$(1270), $a_2$(1320), and $f′_2$(1525) are dominant and a resonance, the $f_2$(2200), is also present. The $f_0$(1710) and possibly the $f_0$(2500) are seen in the S wave. The mass, total width, and product of the two-photon partial decay width and decay branching fraction to the $K \bar {K}$ state $\Gamma _{\gamma \gamma }\mathcal {B}(K \bar {K})$ are extracted for the $f′_2$(1525), $f_0$(1710), $f_2$(2200), and $f_0$(2500). The destructive interference between the $f_2$(1270) and $a_2$(1320) is confirmed by measuring their relative phase. The parameters of the charmonium states $\chi _{c0}$ and $\chi _{c2}$ are updated. Possible contributions from the $\chi _{c0}(2P)$ and $\chi _{c2}(2P)$ states are discussed. A new upper limit for the branching fraction of the P- and CP-violating decay channel $\eta _c \to K^0_S K^0_S$ is reported. The detailed behavior of the cross section is updated and compared with QCD-based calculations.20132017-07-21 12:11:18Znanstveno delo66976sl