The double strangeness exchange reaction (K-, K+) is investigated with respect to the sub-threshold production of scalar and vector mesons (f0/a0/φ) decaying into K+ K- and the two-step processes induced by intermediate mesons and Ξ- hyperons at pK- = 1.66 GeV/c using a scintillating fiber active target. The differential cross section ((dσ/dΩL)) averaged over the angular interval (2.30 ≤ θLK+ ≤ 14.70) for the sub-threshold f0/a0/φ meson production with the K+ K- decay is 11 ± 6 μb/sr at 0.6 ≤ pK+ < 0.95 GeV/c. The present result differs significantly from the theoretical calculation which predicts the contribution of the f0/a0/φ meson production to be predominant in the (K-, K+) reaction below pK+ = 0.95 GeV/c. We found a sizable contribution from two-step (K-, K+) processes, characterized by production of two S = - 1 hyperons, consistent with the result of the intra-nuclear cascade (INC) model calculation with respect to the meson-induced hyperon (or hyperon resonance) pair production in the momentum region 0.6 ≤ pK+ < 0.95 GeV/c. The observed enhancement of the cross section for the two-step ΛΛ production beyond the prediction of the INC model at pK+ ≃ 1.1 GeV/c could be due to the Ξ- p → ΛΛ reaction in 12C.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics