The production of neutral kaons in Z0 decays and their Bose-Einstein correlations

The production of neutral kaons in e+e- annihilation at centre-of-mass energies in the region of the Z0 mass and their Bose-Einstein correlations are investigated with the OPAL detector at LEP. A total of about 1.26 x 106 Z0 hadronic decay events are used in the analysis. The production rate of K0 mesons is found to be 1.99 ± 0.01 ± 0.04 per hadronic event, where the first error is statistical and the second systematic. Both the rate and the differential cross section for K0 production are compared to the predictions of Monte Carlo generators. This comparison indicates that the fragmentation is too soft in both JETSET and HERWIG. Bose-Einstein correlations in K0SK0S pairs are measured through the quantity Q, the four momentum difference of the pair. A threshold enhancement is observed in K0SK0S pairs originating from a mixed sample of K0 anti K0 and K0K0 ( anti K0 anti K0) pairs. For the strength of the effect and for the radius of the emitting source we find values of λ = 1.14 ± 0.23 ± 0.32 and R0 = (0.76 ± 0.10 ± 0.11) fm respectively. The first error is statistical and the second systematic. (orig.)