Medium effects in antikaon-induced Ξ− hyperon production on nuclei near threshold

Abstract We study the antikaon-induced inclusive cascade Ξ − hyperon production from 12C and 184W target nuclei near threshold within a nuclear spectral function approach. The approach describes incoherent direct Ξ − hyperon production in elementary K − p → K + Ξ − and K − n → K 0 Ξ − processes as well as takes into account the influence of the scalar nuclear K − , K + , K 0 , Ξ − and their Coulomb potentials on these processes. We calculate the absolute differential and total cross sections for the production of Ξ − hyperons off these nuclei at laboratory angles ≤ 45∘ by K − mesons with momenta of 1.0 and 1.3 GeV/c, which are close to the threshold momentum (1.05 GeV/c) for Ξ − hyperon production on the free target nucleon at rest. We also calculate the momentum dependence of the transparency ratio for the 184W/12C combination for Ξ − hyperons at these K − beam momenta. We show that the Ξ − differential and total (absolute and relative) production cross sections at the considered initial momenta reveal a distinct sensitivity to the variations in the scalar Ξ − nuclear potential at saturation density ρ 0 , studied in the paper, in the low-momentum region of 0.1–0.6 GeV/c. We also demonstrate that for the subthreshold K − meson momentum of 1.0 GeV/c there is, contrary to the case of its above threshold momentum of 1.3 GeV/c, a strong sensitivity of the transparency ratio for Ξ − hyperons to the considered changes in the Ξ − nuclear potential at all outgoing Ξ − momenta as well, which cannot be masked, as in the case of differential and total observables mentioned above, by that associated with the possible changes in the poorly known experimentally Ξ − N inelastic cross section. Therefore, the measurement of these absolute and relative observables in a dedicated experiment at the J-PARC Hadron Experimental Facility will provide valuable information on the Ξ − in-medium properties, which will be complementary to that deduced from the study of the inclusive ( K − , K + ) reactions at incident momenta of 1.6–1.8 GeV/c in the Ξ − bound and quasi-free regions.