Cross Section Measurements for ¹²C(K⁻, K⁺Ξ⁻) and ¹²C(K⁻, K⁺ΛΛ) Reactions at 1.8 GeV/c

We present a measurement of the production of Ξ⁻ and ΛΛ in the ¹²C(K⁻, K⁺) reaction at an incident beam momentum of 1.8 GeV/c, based on high-statistics data from J-PARC E42. The cross section for the ¹²C(K⁻, K⁺Ξ⁻) reaction, compared to the inclusive ¹²C(K⁻, K⁺) reaction cross section, indicates that the Ξ⁻ emission probability peaks at 70% in the energy region of E_Ξ = 100-150 MeV above the Ξ⁻ emission threshold. A classical approach using eikonal approximation shows that the total cross section for inelastic scattering ranges between 42 mb and 23 mb in the (Formula presented) momentum range from 0.4 to 0.6 GeV/c. Furthermore, based on the relative cross section for the ¹²C(K⁻, K⁺ΛΛ) reaction, the total cross section for Ξ⁻p → ΛΛ in the same approach to vary between 2.2 mb and 1.0 mb in the momentum range of 0.40–0.65 GeV/c. Specifically, a cross section of 1.0 mb in the momentum range of 0.5–0.6 GeV/c imposes a constraint on the upper bound of the decay width of the Ξ⁻ particle in infinite nuclear matter, revealing Γ_Ξ <~ 0.6