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→K0Ξ− processes as well as takes into account the influence of the scalar nuclear K−, K+, K0, 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 ρ0, 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.