Production of φ and f′ in 10 GeV/c K−p interactions

A 4.1 event/nb sample of 11 GeV/c K−p interactions in the LASS spectrometer at SLAC has been used in an analysis of the exclusive Ks0Ks0Λ final state. The Ks0Ks0 mass distribution exhibits a small cluster of events near threshold, but the mass spectrum is dominated by the f2′(1525), which an amplitude analysis shows to be produced by both natural and unnatural parity exchange. This analysis also provides evidence for an S-wave state in the f2′(1525) region, while production of the f2(1720) is not observed. However, there is structure at ∼ 2.2 GeV/c2 which is similar in shape to that observed in the region of the X(2220) in radiative J/ψ decay; an analysis of the angular distribution indicates a spin of at least 2 in this region. This, together with results from other analyses, indicates that the X(2220) may be the 2++ or 4++, mainly ss, state expected near this mass in the conventional quark model.